Verse 15

15)
ato vichaaraH kartavyo jiGYaasoraatmavastunaH ..
samaasaadya dayaasindhuM guruM brahmaviduttamam.h

Therefore ernest inquiry has to be done by him who wishes to know the nature of th Atman approaching in due form the guru who is eminent among those who know Brahman and who is an ocean of compassion.

jiGYaasoh means by one who wishes to know corectly and completely the nature of the Atman. Inquire into the nature of the aatman has to be made as such inquiry gives absolute conviction about what will remove all the evil effects of ajn~ana. The guru is called a dayaasindhu, ocean of compassion; because by eason of himself having achieved his objective (of Brahmavidyaa), he has nothing to gain. Yet, like an ocean filled with water, he is filled with compassion that others should not be subject to the pains of samsaara. He is a reservoir of compassion.

Ajn~ana is compared to darkness because even as physical darknes covering the world is an obstacle to its clear perception, so too the ajn~ana covers the aatman and prevents clear understanding of its nature. Hence the words tamas etc. used synonymously with ajn~ana, in tamo hyaasiit, tamasaa gUlhamagra: 'verily darkness was', 'at first it was concealed in darkness.

Where these two qualities exist in a person (i.e., being a brahmavit and a dayaasindhu), he is called brahmaviduttama. Such persons have realised Brahman; hence they are called brahmaviduh. The best among them is uttama, i.e., one who is sthitaprajN~a, the man of steadfast wisdom. samaasaadya gurum: samaasaadana means duly approaching him as prescribed: having shown reverence to him with devotion, humility and single minded service; and also, by repeated questioning and service to the Guru, It is to be known. The word vimuktyai occuring earlier in sloka 8 has thus been explained in these slokas.