Now let us try to understand each and every word.
What is called ‘being’ is being by virtue of that which remains, ‘being’: that which does not change. If you remember, in the very 2nd chapter Sri Krishna makes a distinction between “that which is” and “that which is not”.
nāsato vidyate bhāvo nābhāvo vidyate sataḥ | (II, 16)
“That which is “is”; that which is not “is not” and can never be”. Reality is real because it cannot be rubbed out. Reality is that which you knock into.
f there is a dark room, you do not know what is there in it, it may be an empty room. What is the proof that something exists there? Something exists because you knock into it: it is there, therefore you knock into it. You come across, you stumble over it because ‘that which is’, that is the mark of it. You cannot rub it out; you cannot think it away; you cannot say that now when I go into the room it will be empty because I think it will be empty. The mark of existence is that you cannot rub it out; you cannot think it away, you cannot wish it away. That which is real is that you are obliged to see: it is that which is independent of your seeing; whether you see or not it exists in itself. It is the real objective reality, uncreated by you; that which is uncreated by you: that which is, it remains what it is.
So, Sri Krishna says akṣaram; akṣaram, means: that is never rubbed out, unchanging. So, first of all you have to see that all knowledge is basically based upon this fundamental point. As long as you have not come to know the ‘immobile’, unchanging, you have not ‘known’. As long as you come to know the mobile, that which is moving, that which was, which will not be, which is now but which is aloof, which is allude you afterwards, as long as you are in that condition you are not in the state of knowledge: ‘Knowledge is always of that which exists’. This is another definition of knowledge: knowledge is always of that which exists. You cannot know that which does not exists. That which does not exists can never become the object of knowledge. Only that can be known that which exists; and that which really exists not that which comes into being and does not exists afterwards. That which exists ‘exists’. As Sri Krishna says: nāsato vidyate bhāvo nābhāvo vidyate sataḥ. That which exists ‘exists’.
That was the first knowledge that Sri Krishna gives to Arjuna, when He says that all those who are wise, they do not talk of ‘killing’ and ‘being killed’: na hanyate nāyaṁ hanti (II, 19).Those who are really seated in knowledge, they are seated in the knowledge of that which is immortal, that which is eternal. So, that which is eternal, that which is immortal is akṣara: it does not change, unchanging, unchangeable. That is akṣaram brahma paramam. Your starting point of knowledge is akṣaram brahma. Now, it is out of this akṣara, svabhāva moves, (svabhāva: bhāva means becoming, sva means oneself). The being which is akṣara, although he is unchanging, he is not incapable of movement; he is immobile but not incapable of mobility. That which is mobile is actually to be seen as svabhāva, there is no movement in the world which is not the becoming of ‘that’ immobile; so, the second term is svabhāva.
Now, why is it called adhyātmam ucyate, svabhāvo ’dhyātmamucyate? This is because there is the word sva: sva means that which the Reality in itself. This is my own, Reality’s own: all movement is actually reality’s own movement. So, one who is in movement…sva is ātman, myself, so the word adhyātma means “the self in movement”. So, either you use the word sva–bhāva, or you use the word adhyātma, it will mean the same thing: adhy–ātma, adhyātma, consists of two words adhy and ātman; ātman is sva; adhy is that which is supervising. The word adhy always means that which supervises; that which is above. That is how we have brought the word adhyakṣa: adhyakṣa,is the chairman, the one who presides, the president is called adhyakṣa. Whenever the word adhy comes, it refers to that which is above; ātma that is above the movement, ātman myself who is in movement, but above the movement, what exhausted in the movement, not eaten away by the movement, that is adhyātma.