aham ātmā guḍākeśa
aham ādiś ca madhyaḿ ca
bhūtānām anta eva ca

Translation of Bhagavad Gita 10.20

I am the Supersoul, O Arjuna, seated in the hearts of all living entities. I am the beginning, the middle and the end of all beings.

Commentary by Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

In this verse Arjuna is addressed as Gudakesha, which means “one who has conquered the darkness of sleep.” For those who are sleeping in the darkness of ignorance, it is not possible to understand how the Supreme Personality of Godhead manifests Himself in various ways in the material and spiritual worlds. Thus this address by Krishna to Arjuna is significant. Because Arjuna is above such darkness, the Personality of Godhead agrees to describe His various opulences.

Krishna first informs Arjuna that He is the soul of the entire cosmic manifestation by dint of His primary expansion. Before the material creation, the Supreme Lord, by His plenary expansion, accepts the purusha incarnations, and from Him everything begins. Therefore He is atma, the soul of the mahat-tattva, the universal elements. The total material energy is not the cause of the creation; actually the Maha-Vishnu enters into the mahat-tattva, the total material energy. He is the soul. When Maha-Vishnu enters into the manifested universes, He again manifests Himself as the Supersoul in each and every entity. We have experience that the personal body of the living entity exists due to the presence of the spiritual spark. Without the existence of the spiritual spark, the body cannot develop. Similarly, the material manifestation cannot develop unless the Supreme Soul, Krishna, enters. As stated in the Subala Upanishad, prakrity-adi-sarva-bhutantar-yami sarva-sesi ca narayanah: “The Supreme Personality of Godhead is existing as the Supersoul in all manifested universes.”

The three purusha-avataras are described in Srimad-Bhagavatam. They are also described in the Satvata-tantra. Visnos tu trini rupani purushakhyany atho viduh: the Supreme Personality of Godhead manifests three features—as Karanodakashayi Vishnu, Garbhodakashayi Vishnu and Kshirodakashayi Vishnu—in this material manifestation. The Maha-Vishnu, or Karanodakashayi Vishnu, is described in the Brahma-samhita (5.47). Yah karanarnava-jale bhajati sma yoga-nidram: the Supreme Lord, Krishna, the cause of all causes, lies down in the cosmic ocean as Maha-Vishnu. Therefore the Supreme Personality of Godhead is the beginning of this universe, the maintainer of the universal manifestations, and the end of all energy.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

First you should think of me alone as the cause of all these vibhutis by one of my portions. I am atma, the soul within prakrti, the creator of the mahat tattva, the purusa, the paramatma (karanodakasayi). O one who conquers sleep (gudakesa), you are qualified for meditation since you do not sleep. I am situated in the aggregate of all beings (vairajas), as the antaryami of the virat (garbhodakasayi). I am also situated within the hearts of all living entities, as the antaryami of the individuals (ksirodakasayi). (Two meanings are given to the phrase sarva bhutasaya stithah). I am the creation (adih), the maintanance (madhyam) and the destruction of all entities.

Commentary by Sri Ramanuja of Sri Sampradaya:

10.20 I am the Self dwelling in the heart of all beings who constitute My body. What is called ‘Self’ is in every way the supporter, controller and the principal of a body. It is further declared: ‘And I am seated in the hearts of all; from Me are memory, knowledge and their removal’ (15.15), and ‘The Lord dwells, O Arjuna in the heart of every being causing them to spin round and round by His power, as if set on a wheel’ (18.61). The Srutis also declare: ‘He who, dwelling in all beings, is within all beings, whom all beings do not know, whose body all beings are, who controls all beings from within, is your Inner Controller, immortal Self (Br. U., 3.7.15); and ‘He who, dwelling in the self is within the self, whom the self does not know, whose body the self is, and who controls the self from within, He is your Inner Controller and Immortal Self’ (Sata. Br., 14.5.30). Thus, I am the Self of all beings and I am their beginning, the middle and also the end. The meaning is that I am the cause of their origination, sustentation and dissolution. Thus, having explained that the Lord’s immanence in all beings, which are His manifestations having Him, as their Self, is the ground for naming them in the manner of Samanadhikaranya or co-ordinate predication with Him (i.e., predication that they are He Himself), Sri Krsna proceeds to present some specific or distinguished manifestations in the same style of co-ordinate predication. As the Lord abides as the Self in all, the final significance of all terms culminates in Him. Terms such as god, man, bird, tree etc., though they signify the respective physical forms of those objects, they culminate through them in the selves in them as their final significance. Just like that here it is going to be stated in the conclusion of the account of the manifestations of the Lord, that the Lord’s immanence in them all as their Self is the basis for describing them in such co-ordinate predication (as He Himself). The text ‘There is nothing, moving or unmoving, apart from Me’ (10.39) says that they are inseparable from Him, and this inseparability is the result of their being under His control. This has been initially declared in the words ‘All proceed from Me’ (10.8). [This word Samanadhikaranya is translated by some also as ‘grammatical co-ordination.’ It is a context in which a number of words, usually having varying denotations, are used to signify an identical object. This kind of co-ordinate relation occurs in all the following verses in which Sri Krsna equates Himself with various objects having different denotations as Atman, Visnu among the Adityas, Indra, Marici, Sankara, Kubera, etc. Further explanation is given in the commentary.]

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

Now commencing Lord Krishna describes the nature of His Supreme Divinity commencing with the reality that He is the Supreme Soul residing in the etheric heart of all sentient beings as monitor of all their thought and actions. Then He reveals that He is the sole cause of all living entities in existence which includes their beginning or origin, their middle meaning their continuance and their ending which means dissolution,

Commentary by Sri Madhvacharya of Brahma Sampradaya:

Sri Madhvacharya did not comment on this sloka.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

Before Lord Krishna commences speaking of His transcendental glories He describes His glorious divine spiritual form. The words sarva-bhutasaya- sthitah means abiding in the heart of all sentient beings. How? As paramatma the Supreme Soul residing within the atma or individual soul which all collectively comprise His transcendental, spiritual body. The Supreme Lord Krishna is the beginning meaning creation, the middle meaning sustenance and the end meaning destruction of all living entities along with all insentient elements. The Supreme Lord uses the address Gudakesa meaning one who has control over sleep which indicates that Arjuna has the ability to be ever wakeful and aware.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

10.20 Gudakesa, O Gudakesa-gudaka means sleep, and isa means master; master of that (sleep) is gudakesa, i.e. one who has conquered sleep; [See also under 1.24.-Tr.] or, one who has got thick hair; aham, I; am the atma, Self, the indwelling Self; who is to be ever-meditated on as sarva-bhuta-asaya [Asaya-that in which are contained the impressions of meditations (upasanas), actions and past experiences.]-sthitah, residing in the hearts of all beings. And, by one who is unable to do so, I am to be meditated on through the following aspects. I am capable of being meditated on (through them) becasue aham, I; am verily the adih, beginning, the origin; and the madhyam, middle, continuance; ca, as also; the antah, end, dissolution; bhutanam, of (all) beings. ‘I am to be meditated upon thus also:’

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

10.19-42 Hanta te etc. upto jagat sthitah. I am the Soul etc. (verse 20) : By this [the Bhagavat] wards off the exclusion [of any being as different form Him]. Otherwise the sentences like ‘Of the immovable [I am] the the Himalayas’ (verse 25) etc., would amount to the exclusive statement that the Himalayan range is the Bhagavat and not any other one. In that case, the indiscriminateness of the Brahman is not established and hence the realisation of the Brahman would be a partial (or conditioned) one. For, the [present] text of exposition is intended for that seeker whose mind cannot contemplate on the all-pervasiveness [of the Brahman], but who [at the same time] is desirous of realising that [all-pervasiveness]. Hence, while concluding, [the Bhagavat] teaches the theory of duality-cumunity by saying ‘whatsoever being exists with the manifesting power’ etc., and then concludes the topic with the theory of absolute unity, as ‘Or what is the use of this elaboration;…..I remain pervading this [universe] by a single fraction [of Myself] This has been declared indeed [in the scriptures] as : ‘All beings constitute [only] His one-fourth; His [other] immortal three-forths are in the heaven.’ (Rgveda, X, xc, 3). Thus, all this and the prime cause of creatures, are nothing but the Bhagavat (Absolute). And hence, He Himself becomes the object of knowledge of all, but being comprehended with the different strange qualities.

Sanskrit Shloka Without Transliteration Marks:

aham atma gudakesa
aham adis ca madhyam ca
bhutanam anta eva ca

Sanskrit to English Word for Word Meanings:

aham — I; ātmā — the soul; guḍākeśa — O Arjuna; sarva-bhūta — of all living entities; āśaya-sthitaḥ — situated within the heart; aham — I am; ādiḥ — the origin; ca — also; madhyam — middle; ca — also; bhūtānām — of all living entities; antaḥ — end; eva — certainly; ca — and.