Orthodox Indian philosophy, the legacy of the Indo-Aryans, takes on a much different form than it does in the West, and in turn a much different form that it does in the Far East, despite the fact that the intellectual developments – if we can group them all collectively into the Western centric term philosophy which in and of itself is somewhat misleading of course – all take place at roughly the same time, from roughly the turn of the first millennium BCE to the 2nd or 3rd centuries BCE give or take. As part of this intellectual development in India in the first half of the first millennium BCE, the Upanishadic literature is compiled and included directly into the Vedic corpus.
The Upanishads, 108 of them in all in the orthodox tradition, despite being rooted in the ancient mythos of the Indo-Aryans, is an altogether different form than the older layer of Vedic literature which is more concerned with hymns to the gods, sacrificial and the like, albeit traces of these theo-philosophical beliefs can be found in the older strata of the Vedas themselves. The Upanishads however, are primarily concerned with more esoteric matters than the performance of rituals or sacrifices, and as such they form the foundation of all subsequent “orthodox” Indian philosophy.
One of the prevailing etymologies of the word Upanishad is that it is derived from the Sanskrit root sad, which means to ‘to loosen’ or ‘to attain’ (or even ‘to annihilate’), which is combined with the prefixes upa and ni, which denote ‘nearness’ or ‘sitting beside’ as well as ‘totality’. In this sense, the word Sanskrit word Upanishad can be thought of as referring to not only the process by means this ancient knowledge was passed down from antiquity, i.e. the sitting beside and learning from a teacher versed in the knowledge of Brahman, but also the wisdom of the teachings themselves which are embedded in the texts. Upanishad then in this context can be seen as a sort of veiled reference to the content of the Upanishadic literature itself, i.e. Brahmavidyā, or knowledge of Brahman, and Atmavidyā, or knowledge of Self, or Ātman.
One of the advantages we have when parsing through the (Primary) Upanishadic literature, some crafted in prose and some in verse, although we enter a distant realm of myth and allegory (as the Upanishads are rooted directly in the mythological and ancient sacrificial and ceremonial worship traditions that are so predominant in the Vedas), we nonetheless have the advantage of the familiarity with some of the basic Sanskrit terms that underpin Vedic philosophy that have already made it more or less into English vernacular. Brahman and Ātman for example, are for the most part terms that are familiar to the Western reader, just as Yahweh or Zeus are also familiar terms. This is due primarily to the efforts of many scholars in the late 19th and throughout the 20th century who introduced Vedānta, and its offshoot Buddhism, to the West, the most prominent of these figures are perhaps Max Müller, Swami Vivekananda and Swami Nikhilananda, each of which made major contributions to the diffusion and familiarization of Eastern philosophy, and in particular Vedānta, to the West.
Translations of these ancient texts are still notoriously difficult however, and to come to a true understanding of the meaning behind many of the passages, it is necessary to consult several different translations as we do in the subsequent text, all the while not only trying to establish the foundational passages, or sūtras, that illustrate what we come to know as “Vedānta”, but also establishing parallel intellectual developments within the Hindu and Indo-Aryan theo-philosophical developments of the first millennium BCE that correspond quite closely to evolutions (revolutions really) that occurred in the area of Hellenic influence in the Mediterranean and the area of Chinese influence in the Far East.
To this end we have selected some passages from some of the most influential of the Primary Upanishads that not only reflect the core part of Vedic philosophical inquiry as it takes shape in the form of Vedānta in the first millennium CE, but illustrate its theo-philosophical integration and synthesis into the prevailing Vedic mythos which represents the heart of the Indo-Aryan theo-philosophical tradition in the first millennium BCE when most of the core Upanishads are believed to have been composed. This is one of the unique characteristics of Indian philosophy in fact, i.e. the unbroken lineage between the ancient mythos of the Indo-Aryans and their “philosophy” – as it is understood in its earliest forms through the Upanishadic literature – all embedded within the same corpus as it were, i.e. the Vedas.
The first passage is from the influential Īśo Upanishad, or Isha Upanishad, which is a brief set of sūtras or verses, 17 or 18 in all depending upon the recension of the text (there are two extant), and is found at the end of the Samaveda. It pertains to the nature of the Lord, or “Isha”, and so comes by its name.
ALL this, whatsoever moves on earth, is to be hidden (clothed, enveloped) in the Lord [Isha]. When thou hast surrendered all this, then thou mayest enjoy; lust not after any man’s possession.
Though a man may wish to live a hundred years, performing works, it will be thus with him; but not in any other way: work will thus not cling to a man.
There are the worlds of the Asuras(gods, or literally ‘beings without light’) covered with blind darkness. Those who have destroyed their Self (Ātman), go after death to those worlds.
One unmoving that is swifter than Mind, That the gods [devas] reach not, for It progresses forever in front. That, standing, passes beyond others as they run. In That the Master of Life [Mātariśvan] establishes the Waters [Āpas].
It stirs and it stirs not; it is far, and likewise near. It is inside of all this, and it is outside of all this.
And he who beholds all beings in the Self (Ātman), and the Self in all beings, he never turns away from it.
When to a man who understands, the Self has become all things, what sorrow, what trouble can there be to him who once beheld that unity?
It is He that has gone abroad – That which is bright, bodiless, without scar of imperfection, without sinews, pure, unpierced by evil. The Seer [kavi], the Thinker [manisi], the One who becomes everywhere, the Self-existent has ordered objects perfectly according to their nature from years sempiternal (eternity).
Into a blind darkness they enter who are devoted to Asambhuti (unmanifested Prakṛti); but into a greater darkness who on Sambhuti (manifested Prakṛti) are intent.
One thing, they say, is obtained from Sambhava; another, they say, from Asambhava. Thus we have heard from the wise who taught us this.
The man who knows Sambhuti (manifested Prakṛti) and Vinasa (destruction) simultaneously, He, by Vinasa (destruction) passing death, gains by Sambhuti (manifested Prakṛti) endless life..
Into a blind darkness they enter who worship only ignorance [avidyā]; but into a greater darkness they enter who worship of knowledge [vidyā].
One thing, they say, is obtained from knowledge [vidyā]; another, they say, from ignorance [avidyā]. Thus we have heard from the wise who taught us this.
He who knoweth both knowledge [vidyā] and ignorance [avidyā], overcomes death and obtains immortality.
The door of the Truth is covered by a golden disk. Open it, O Pûshan [Nourisher]! Remove it so that I who have been worshipping the Truth may behold it.
O Fosterer, O sole Seer, O Ordainer, O illumining Sun, O power of the Father of creatures, marshal thy rays, draw together thy light, the Lustre which is thy most blessed form of all, that Thee I behold. The Puruṣa there and there, He am I.
The Breath of things [Vāyu] is an immortal Life, but of this body ashes are the end. Om! O Will [kratu], remember, that which was done remember! O Will, remember, that which was done remember.
Agni, lead us on to wealth (beatitude) by a good path, thou, O God, who knowest all things! Keep far from us crooked evil, and we shall offer thee the fullest praise! (RV. I, 189, 1.).
While the language of the Upanishads in general are notoriously difficult to translate into modern English given the terminology and Sanskrit terms that are used, words that can only be understood in the context of the Vedic mythos within which it comes from and sits beside, the Upanishad still nonetheless is still representative of the emergence of “philosophical” inquiry, what can truly be known, that takes place toward the end of the Vedic period of Indo-Aryan history.
The text attempts to describe the nature of knowledge and its relationship to Ātman, or the Self as it is usually translated (Soul would probably be a better translation into classic Judeo-Christian nomenclature), all within the Vedic historical, ritualistic and theistic tradition to which it is ultimately a part of hence its inclusion in the Vedas.
Isha, or Lord, is appealed to in the first verse, from which the Upanishad again gets its name, and in this sense the Upanishad, although it is “philosophic” in nature (hence its categorization as one of the primary Upanishads) is nonetheless a theistic conception from start to finish, despite its appeal to knowledge of Self, i.e. the nature of Soul, as the source of immortality.
The 4th verse uses the term Mātariśvan, which although variously rendered into English really has no English counterpart. It can be understood in terms of a literal translation from the Sanskrit as “growing in the mother”, from the root for “mother”, or “mātari”, and “śvi”, or “to grow” or “swell”. The term is used in the Rigvéda an epithet for Agni, one of the prominent deities of Vedic and Purāṇic mythos, the fire deity who presides over the sacrificial fire (yajña) which is such an essential part of much of Vedic worship. In the Atharvaveda and later, the term is used as an epithet of Vāyu, the lord of the winds and in this context the word has the meaning of “air”, “wind”, or “breeze” which represents the divine breath, or life energy as denoted by the Indian theo-philosophical principle of prāṇa which plays such a prominent role in (later development of) Yogic philosophy. Vāyu is also referred to specifically in the 17th verse as well, as the embodiment of immortal life, as is Agni who is appealed to in the final verse as the embodiment of all knowledge.
The 4th verse also makes reference to the “Waters”, or āpas, which in this sense is used to symbolize the material universe but nonetheless has specific connotations as one of the primordial elements of creation, akin to much of Eurasian mythos in fact where the beginning of the universe is characterized as a watery abyss, or chaos, from which order is established by the primordial deity or cosmic being who through Eros, love, or desire, creates the great cosmic egg (Hiraṇyagarbha) from which the Heaven and Earth and all of creation, and the first great pantheon of deities, emerge.
Verses 9-11, which sit in direct contrast to verses 12-14, call out the delusion – again darkness – that comes from the worship of Sambhuti, or manifested existence, or the worship of its opposite, Asumbhuti, or unmanifested existence. These terms are replaced with their philosophic counterparts – knowledge (vidyā) and ignorance (avidyā, or lack of knowledge) – in verses 12-14, but the message in all 6 of these verses is essentially that by understanding the nature of existence and non-existence, the nature of knowledge and ignorance, death itself can be overcome.
We also see in verses 16 and 17 reference to Pushan, the Vedic solar deity, who is appealed to as the preserver of livestock, the presider over marriage, and appealed to as the protector for journeys, seen in some references as the deity responsible for driving the sun across the sky, very much akin to the sun god Ra of Egyptian mythology in fact. This “golden disk”, which sits over or veils, Truth and knowledge is appealed to in the 5th verse as well. In Vedic mythos, the sun god is called Sūrya, and later comes to represent the “illumined” deities who sit in contrast and opposition to Asūryas, or those beings which are not illumined, and it is in this meaning that is called out specifically here, rather than the more literal deity of the Sun, who is nonetheless appealed to as Pushan.
Some of the language we find here in the Īśo Upanishad, as reflected in verses 4-6 for example, is a very classically “Eastern” philosophic technique, where the nature of reality, or knowledge in this case, is described via the use of very dense and seemingly contradictory language, via the description of what it is not for example versus what it is. Some of the same types of language, in verse, can be found in the early Daoist literature for example, or in the early Hellenic philosophic fragments attributed to Parmenides and even Heraclitus.
All of these works share the common theme of attempting to explore and describe the nature of reality – that which is, to eon, versus that which is not as described by Parmenides for example – in sharp and distinct verse, and all seem to share a similar attribute of describing such an abstract principle using metaphorical language, and in many cases language that that uses contrarian and opposing principles to try to convey meaning. This seems to be a wide ranging linguistic tool that is used throughout antiquity, almost always couched in harmonic verse, from which knowledge of truth or Ultimate Reality is conveyed to the reader, or in almost all cases from teacher to student which is how these messages were conveyed in pre-historic times, i.e. before these texts were written down in the middle of the first millennium BCE.
So despite the “philosophic” content of the Upanishad, and the reference to knowledge (vidyā) and its counterpart ignorance (avidyā), we nonetheless are confronted with a whole wealth of symbolism from Vedic mythos within which this truth can be ascertained, with the presumption of the basic immortality of the Soul (Ātman), knowledge of Self, being represented as not only the ultimate purpose behind the rituals and sacrifices which are outlined as the core content of the Samaveda corpus within which this Upanishad, but also the knowledge of which, true understanding in fact, death itself can be overcome. So Self, Ātman, and knowledge or truth, are held to be equivalent from an epistemological perspective here, and this is one of the all-pervading themes that tie together all of Upanishadic philosophy.
From the Muṇḍaka Upanishad, a set of 64 verses found embedded in the Atharvaveda, we find once again the attempt at the explanation of knowledge, vidyā, in this case delineating between lower and higher forms of knowledge, and the introduction of the concept of Brahman, which exists beyond the senses and material world and yet at the same time from which the material universe in all its names and forms emanate.
Om. Brahmā, the Maker of the universe and the Preserver of the world, was the first among the devas. He told His eldest son Atharva the Knowledge of Brahman, the foundation of all knowledge.
Whatever Brahmâ told Atharvan, that knowledge of Brahman Atharvan formerly told to Aṅgir; he told it to Satyavâha Bhâradvâga, and Bhâradvâga told it in succession to Aṅgiras.
Saunaka, the great householder, approached Aṅgiras respectfully and asked: ‘Sir, what is that through which, if it is known, everything else becomes known?’
He said to him: ‘Two kinds of knowledge must be known, this is what all who know Brahman tell us, the higher and the lower knowledge.’
Of these two, the lower knowledge is the Rigvéda, Yajurveda, Sâmaveda, Atharvaveda, Sikshâ (phonetics), Kalpa (ceremonial), Vyâkarana (grammar), Nirukta (etymology), Khandas (metre), Gyotisha (Astronomy); but the higher knowledge is that by which the Indestructible (Brahman) is apprehended.’
‘That which cannot be perceived, which cannot be seized, which has no origin, which has no properties, which has neither ear nor eye, which has neither hands nor feet, which is eternal, diversely manifested, all-pervading, extremely subtle, and undecaying, which the intelligent cognized as the source of the Bhutas (all beings/things).’
‘As the spider sends forth and draws in its thread, as plants grow on the earth, as from every man hairs spring forth on the head and the body, thus does everything arise here from the Indestructible.’
‘Brahman expands by means of austerity [tapas], and from It food (material existence) is produced; from food are born Prāṇa, Mind [manas]; Truth [satya] and the worlds; and from work [karmasu] proceed the immortal results.’
‘For him who knows all and understands everything, whose austerity [tapas] consists of knowledge – from Him, the Imperishable Brahman, are born Brahmā, name, form, and food (matter).’
Here we find the exposition of knowledge as understood as knowledge of Brahman, which is conceived in the Vedas and in particular in the Upanishads as a whole as the Supreme or Ultimate Reality, the great Cosmic principle which underlies the entire universe, very much akin to Plato’s Demiurge in fact. This Upanishad begins with the statement that this higher form of knowledge, Brahmavidyā, originates from Brahmā himself at the beginning of the cosmic cycle, Brahmā representing the anthropomorphic creator of the universe in Vedic mythos. In the Vedas, Brahmā is associated with Prajāpati, literally “lord of people”, who is viewed as the preserver and maintainer of human existence and the creation of life.
Brahman in this context as introduced in the first verse, and in fact throughout the Upanishadic literature, represents a significant departure from the focus on the anthropomorphic construction of the material universe embedded and narrated in mythological terms and metaphors, to a more metaphysical notion of the Cosmos denoting Ultimate Reality, Cosmic Mind, or World Soul, i.e. Brahman which of course etymologically is derived from the epithet of the great creator god of the Vedas, Brahmā.
The “lower” forms of knowledge are delineated first, being represented not only as the ritual worship, sacrifices and rituals that are described in all of the four Vedas, but also what we would consider to be more “academic” forms of knowledge as well, described as the intellectual disciplines of the study of grammar, ceremonial worship, the etymology and meaning of words and texts (the study of language basically), meter and song (music and ceremonial worship), as well as even Astronomy. This set of “lower” knowledge is analogous to the philosophical discipline which emerges in the area of Hellenic influence to the West in fact, where the study of “philosophy” becomes synonymous with not just the study of the nature of the universe, i.e. that which is subject to change, but also – as the discipline of philosophy matures with the emergence of the Stoic and Epicurean schools for example – the study of language and rhetoric, physics and Astronomy, and mathematics as well, all grouped together as the “curriculum” as it were of the various philosophical schools as they mature in classical Greek antiquity.
But in verses 6 and 7, it is Brahmavidyā, knowledge of Brahman, that is called out as the higher form of knowledge, knowledge which is beyond the senses, is eternally manifest, is not subject to change (i.e. undecaying as it is translated here) and is the source of the material universe, i.e. everything that is subject to change. As described in the 8th verse, it is from Brahman that comes forth the basic material from which the universe is constructed – here translated as “food” but conceptually more akin to the later philosophical conception of the unmanifested material from which the universe is constructed, i.e. Prakṛti in Sāṃkhya philosophy – and from this basic material, these primordial elements, the cosmic breath or energy, i.e. prāṇa, is created which gives sentient life to the universe as well as mind, manas, which breathes intelligence, or order, into the universal creation, as well as Truth itself (satya), and all the “worlds” – the physical world as well as all of the spiritual or ethereal worlds which the deities inhabit as well.
Austerity here, the term tapas in Sanskrit, is called out specifically as the means by which this higher form of knowledge, i.e. Brahman, is ‘expanded’ or perhaps better put, comes to be understood. Tapas is a very loaded Hindu philosophical term which comes from the Sanskrit root tap (तप्) which means “to heat”, “to shine”, or “to burn”, alluding to the very ancient, and at the same time very common belief (common across virtually all Western Eurasian theo-philosophical systems in antiquity in fact) that the highest forms of knowledge, knowledge of the divine source of all, i.e. Ultimate Reality, come about through a process of “illumination”, or “burning” or “heating”, one which is driven by the basic material element of fire and a process by which the individual psyche (Ātman in the Vedic tradition) is transformed into higher states of understanding and cognition.
Hence the significance of Agni as one of the primordial deities in Vedic mythos and the presider over yajña, the core sacrificial rites which are to be performed over and using the sacred element of fire. In later philosophical conceptions, as understood through the lens of Vedānta as interpreted by Srī Śaṅkara for example, tapas comes to be understood to relate directly to, and is typically translated as, “austerity” or “austerities”, representing the spiritual practices and abstentions which were associated with the monastic followers of Hinduism (and Buddhism). Here we see one of the etymological derivations of the title of the Upanishad, Muṇḍaka, which means literally “shaven”, which is believed to be a thinly veiled reference of the “shaven” head of the Hindu monk.
The Kena Upanishad is also part of the Samaveda corpus and consists of a combination of prose and poetic verse divided into four chapters, or khandas. The first two chapters are a dialogue between a teacher and student which starts off as the student querying the teacher as to the nature of the ultimate cause, or source of all things. The teacher then goes on to explain the nature of Brahman, from which all true knowledge, as well as material existence itself, emanates from. The last two chapters narrate the story of Brahmā appearing before Indra, Agni and Vāyu as a divine (female) spirit after they have just won their epic battle against the lesser gods (devas) in order to help them understand that it is through his will, or perhaps better put through the power vested in Brahmā alone, that their enemies were overcome.
The title of the Upanishad gets its name from the first word of the text, “Kena”, which loosely translated into English means something along the lines of “by what”, “by whom”, “whence”, “how”, or “from what cause”, reflecting not only the underlying topic of the work as an exposition of Brahman as the underlying cause of the material universe and all its inherent life and events, but also reflecting the skeptical epistemological thread that runs through most of Upanishadic philosophy. The work is one of the Mukhya, or Primary, Upanishads and it is also one of the most influential and most oft translated, the translation of the first two chapters, khandas, is presented below.
I.1. The Student asks: ‘At whose wish does the mind sent forth proceed on its errand? At whose command does the first breath [prāṇa] go forth? At whose wish do we utter this speech? What god (effulgent one) directs the eye, or the ear?’
I.2. The Teacher replies: ‘It is the Ear of the ear, the Mind of the mind, the Speech of speech, the (breath) of the prāṇa (breath), and the Eye of the eye. Knowing this, the wise, having relinquished all false identification of the Self [Ātman] with the senses, become immortal, when departed from this world.
I.3/4. ‘There goes neither the eye, nor speech, nor mind; we know It not: nor do we see how to teach one about It. Different It is from all that are known, and is beyond the unknown as well – thus we have heard from the ancient seers [rishis] who explained That to us.
I.5. ‘What cannot be expressed by speech, but by which speech is expressed, know that alone as Brahman and not this which people here worship.
I.6. ‘What none can comprehend with the mind, but by which, the sages say, the mind is comprehended, know that alone as Brahman and not this they worship here.
I.7. ‘What none can see with the eyes, but by which one can see, know that alone as Brahman and not this they worship here.
I.8. ‘What none can hear by the ears, but by which one can hear – know that alone as Brahman and not this they worship here.
I.9. ‘What none can breathe by breath but by which we can breathe, know that alone as Brahman and not this they worship here.
II.1. The Teacher says: ‘Thou knowest indeed very little of Brahman’s form, if thou thinkest, ‘I know It well.’ What thou knowest of this Brahman among the gods is also very little. Therefore the nature of Brahman is still to be ascertained by thee.’.
At this, the disciple thought more deeply of Brahman within himself and realized It; then he came to the teacher and said, ‘Now I think it has become known to me.’
II.2. The Student continues: ‘I do not think I know It well, nor do I know that I know It not. He among us knows It truly who knows this – namely (viz.), that I know that I know It not.
II.3. ‘Brahman is truly comprehended by him who knows It is incomprehensible; he knows It not who thinks It is comprehended by him. It is unknown to those who know and known to those who do not know.
II.4. ‘Brahman becomes really known when It is realized in all states of consciousness. Through that knowledge man attains immortality. By the self man attains strength, by the Knowledge immortality.
II.5. ‘If a man know It here, then there is truth; if he does not know this here, then there is great destruction. The wise having realized that Ātman in all beings become immortal, on departing from this world.’
We see some common themes here from the last two passages, with the delineation of higher and lower forms of knowledge, even though they are not explicitly called out as such. The belief and exposition of the way of “immortality”, as attained by the attainment of the highest knowledge, knowledge of the Self (Ātman). But it is the knowledge of Brahman that is expounded upon here and perhaps has the greatest emphasis, and its relationship to comprehensibility itself. To paraphrase: “those who know It know it not, and those who do not know It in turn know it’. The language used to describe this knowledge, the skeptical epistemological bent that is reflected, are all core characteristics of Upanishadic philosophy.
We also see here the distinction drawn, again a common theme throughout much of the Upanishadic philosophy, between knowledge gained by the senses (lower form of knowledge) and that which rests behind the senses and allows them to “function”, or “perceive”, i.e. Brahman or the highest form of knowledge. This higher form is what yields immortality, another constant theme of the Upanishadic philosophical tradition. That the Soul (Ātman) not only exits, but that its true nature is not only undying and undecaying, i.e. immortal, but that it in turn is non-different from, and essentially united with, none other than the ever present imminent and all-pervading Brahman – the source of all and that which permeates and gives life to the entire cosmos.
The style of the language here is again worth noting. Even in the English translation the poetic verse comes through, which does not only serve utilitarian purposes as it makes the transmission of the text easier from teacher to student, but it also lends itself toward repetition and contemplation, thereby serving the ultimate purpose of bringing one closer to, and helping illuminate, the topic of Upanishad itself, namely the highest knowledge, that of Brahman, by means of death itself can be overcome. Also the contradictory and opposing terms and meanings are used throughout the first two khandas, a characteristic that is shared in much of the early theo-philosophical tradition not only in the Upanishads, but also in some of the early theo-philosophical texts from the Far East, in the Daoist texts in particular, and in some of the fragments we find from the Pre-Socratics a well, in the poem attributed to Parmenides for example.
Outside of the esoteric notions of Brahman and Ātman which are explored and eulogized in the more esoteric parts of Vedic scripture, there does also exist in the tradition a parallel notion of anthropomorphic deities consistent with the pantheon of gods that colored the mythology of the rest of the cultures from antiquity – the Greeks, Persians, Romans, Egyptians, etc. This concept of God, or Īśvara, is present in the Upanishads and the Vedas as well for example, and is common theme for post Vedic literature such as can be found in the Purāṇas for example. But this anthropomorphic being or metaphysical construct as it were, and the ceremonial worship and sacrifices to which it is associated, becomes a secondary principle in the Upanishads, a form of “lower” knowledge. So while not altogether rejected, as it is say in the theo-philosophical traditions of the ancient Chinese or in the classical Greco-Roman philosophical tradition, it is nonetheless granted a secondary position and is called out as an inferior form of knowledge relative to the notion of Brahman, one of the core metaphysical notions that is introduced and discussed at length in the Upanishadic philosophical tradition who/which is beyond the conception of the human mind and is most certainly beyond the language divined by humans to describe the world around them.
In the Upanishads, Brahman is the universal spirit that underlies all creation and Ātman, the Soul, is that which is universal and all pervasive in each of us individually and which is intimately connected to Brahman and through contemplation of this unity death itself can be overcome. Brahmavidyā in turn is the knowledge of this ineffable and indivisible construct of Brahman. The concept of Brahman as espoused in the Upanishads is the belief in the ultimate unity of all things and creatures, animate and inanimate, and the belief in an indelible construct or consciousness which pervades the entire universe and which feeds and gives energy to our souls, or Ātman, as well as is the source of all animate and inanimate creatures, and from which the material universe, in all its forms, stems from and is supported and maintained by.
The core premise of the Upanishads then can be seen as the belief in not only the existence of the immortal Soul, i.e. Ātman, but also the indivisibility of the individual Soul and the Cosmic Soul, i.e. Brahman, coupled with the idea that each and every one of us, through the contemplation of the verses and meaning behind the Vedas and the Upanishads, what came to be known as the “end of the Vedas” or Vedānta, that this higher knowledge, vidyā, that which is permanent and non-changing and is beyond the world of sense perception which is subject to constant change, i.e. impermanence (which becomes an important philosophic construct in the Buddhist tradition for example), is the very source of immortality, the tree of life. And It can in turn, through tapas – the practice of “austerities”, contemplation and the lading of a virtuous life aligned with the teachings of the Vedas, in fact can be “realized” and is the very essence of the teaching of the Upanishadic philosophy in all its various forms throughout the Vedic corpus.
 Isha is the root as Īśvara, one of the epithets of the Lord of the Universe in Hinduism.
Translation renderings from Max Müller, 1879 The Upanishads, Part 1 (SBE01), “VÂGASANEYI-SAMHITÂ-UPANISHAD” at http://www.sacred-texts.com/hin/sbe01/sbe01243.htm, Swami Nikhilananda The Upanishads, Volume One. Ramakrishna-Vivekananda Center of New York, 6th edition published in 2003. “Isa Upanishad”, pgs. 204 ff. and Isha Upanishad, Volume 17 The Complete Works of Srī Aurobindo, Srī Aurobindo Ashram Trust, 2003. Part One, pgs. 3 ff. The texts of the White Yajurveda by Ralph T. H. Griffith, 1899. Pgs. 305 ff. also consulted.
See Wikipedia contributors, ‘Mātariśvan’, Wikipedia, The Free Encyclopedia, 27 November 2015, 03:13 UTC, <https://en.wikipedia.org/w/index.php?title=M%C4%81tari%C5%9Bvan&oldid=692626106> [accessed 4 October 2016] and Isha Upanishad, translation and commentary by Srī Aurobindo. Volume 17, The Complete Works of Srī Aurobindo. Published by Srī Aurobindo Trust, 2003. Part 1, page 6 note 5.
 Srī Aurobindo also notes, “But the Waters, otherwise called the seven streams or the seven fostering Cows, are the Vedic symbol for the seven cosmic principles and their activities, three inferior, the physical, vital and mental, four superior, the divine Truth, the divine Bliss, the divine Will and Consciousness, and the divine Being. On this conception also is founded the ancient idea of the seven worlds in each of which the seven principles are separately active by their various harmonies.” See Isha Upanishad, translation and commentary by Srī Aurobindo. Volume 17, The Complete Works of Srī Aurobindo. Published by Srī Aurobindo Trust, 2003. Part 1, page 6 note 6.
 Vidyā is Sanskrit for “correct knowledge” or “clarity”, and comes from the same Indo-European root as the verb “to see”, which in Latin is vidēre.
See Hymn 1.115, CXV “Sūrya” of the Rigvéda where he is described as leading the Sun across the darkness of Night, led by a team of horses, again very reminiscent of the sun god Ra in Egyptian mythology as well as Helios in Hellenic mythos. See Rigvéda, translated by Ralph T.H. Griffith, 1896 at http://www.sacred-texts.com/hin/Rigvéda/rv01115.htm. Also see Wikipedia contributors, ‘Pushan’, Wikipedia, The Free Encyclopedia, 1 October 2016, 08:29 UTC, <https://en.wikipedia.org/w/index.php?title=Pushan&oldid=742037923> [accessed 3 October 2016], Wikipedia contributors, ‘Sūrya’, Wikipedia, The Free Encyclopedia, 3 October 2016, 07:27 UTC, <https://en.wikipedia.org/w/index.php?title=Sūrya&oldid=742363016> [accessed 4 October 2016], and Isha Upanishad, translation and commentary by Srī Aurobindo. Volume 17, The Complete Works of Srī Aurobindo. Published by Srī Aurobindo Trust, 2003. Part 1, page 9 note 10.
 Muṇḍaka in Sanskrit means “shaven” or “shorn”, like the trunk of a tree for example. While the etymology of the title of the work is disputed, scholars generally agree that it is so named because either a) the ‘shaven’ or true nature of Brahman is revealed in the Upanishad, or b) referring to the shaven head of the sannyasin, or Hindu monk, to which this particular Upanishad is supposedly geared towards, or c) both.
 Translation from Max Müller, 1879 The Upanishads, Part 2 (SBE15), “MUṆḌAKA-UPANISHAD” from http://www.sacred-texts.com/hin/sbe15/sbe15016.htm and Swami Nikhilananda The Upanishads, Volume One. Ramakrishna-Vivekananda Center of New York, 6th edition published in 2003. “Muṇḍaka Upanishad”, pgs. 261 ff. Swami Krishnananda’s translation also consulted (verse 9) from http://www.swami-krishnananda.org/mundak/Muṇḍaka_Upanishad.pdf as well as S. Sitarama Sastri Muṇḍaka Upanishad translation published by V. C. Seshacharri 1905 in Madras at http://www.wisdomlib.org/hinduism/book/Muṇḍaka-upanishad-Śaṅkara-bhashya#contents. Also consulted Sanskrit and English translation and (Srī Śaṅkara) commentary at Red Zambala, 2013 at http://redzambala.com/upanishad/Muṇḍaka-upanishad-english-sanskrit.html.
 In the Purāṇas, the more mature rendition of Hindu mythos that comes together after the Vedic period, a Trinity of gods emerge which are referred to as the “Trimurti” – or literally “three forms” in Sanskrit – of which Brahmā represents the creative force from which the universe emanates at the beginning of a universal cycle, Viṣṇu then is represented as that aspect of God who preserves the universe during the cycle, and then Śiva is seen as the destructive (or transformative) force which brings the cycle to a close after which the cosmic cycle then begins again.
 While the third chapter, or again khanda, is typically interpreted as an allegorical representation of the overcoming of the senses (devas) by the Soul by which knowledge of Brahman can be “realized” (for lack of a better term) the final khanda deals directly with the teaching of the nature of Brahman as well, although in this context the teaching is directed to the Indra, Agni and Vāyu, the great triad of deities in the Vedas, rather than to a mere mortal student, emphasizing the divine and imminent nature of the teachings, and of course of the nature of Brahman itself, as an primordial ontological metaphysical construct even when viewed from a divine perspective. That is to say, one of the points of the final chapter is to emphasize that knowledge of Brahman, and the results of the attainment of knowledge of Brahman, i.e. immortality, is the goal not just of mortal beings, but also of the so-called “immortals” as well.
 Translation primarily taken from Max Müller, 1879 The Upanishads, Part 1 (SBE01), “KENA-UPANISHAD” from http://www.sacred-texts.com/hin/sbe01/sbe01176.htm and as well as the translation and commentary by Swami Sharvananda from his work Kena-Upanishad, published by the Ramakrishna Math, Madras 1920. Swami Nikhilananda’s translation also consulted from The Upanishads, Volume One. Ramakrishna-Vivekananda Center of New York, 6th edition published in 2003. “Kena Upanishad”, pgs. 2229 ff..