So we are not beginning from the gross stage. The Bhagavad-gītā, although it is A-B-C-D of spiritual instruction, it begins from that stage, which stage the jñānīs, the philosophers, and the yogīs, they are trying to reach. But we have no time. In this age by yoga practice, to come to this stage, that "I am not this body . . ." Ask any student who are practicing yoga, so-called meditation, they are inclined to this body. They are trying to exercise this body, and they think that this is the final. No.
Simple truth, very simple truth: Kṛṣṇa, as the supreme authority, presenting very simply, that dehino 'smin yathā dehe kaumāraṁ yauvanaṁ jarā (BG 2.13). As in this body there are different changes, similarly the ultimate change is called death. But the spirit soul, as he's existing within this body in spite of all changes.
Similarly, the spirit soul will continue to exist even after the final change of this body. This simple truth. Try to understand this. This is the basic principle of further progress. If one does not understand this point of view, there is no progress. This is A-B-C-D, that "I am not this body."
Read on.