In plain words
did this 'I' exist before being born? If it existed, then birth does not apply to something that already exists, does it? Then, before birth, how did it exist? Where was this 'I,' then? Was it something distinct from the body and such, or did it exist beyond the senses? Such doubts surge up like a flood. Actually, it becomes clear that the word 'I' does not pertain to any single thing, individual, or particular name and form. Therefore, whoever first recognises this [reality of] 'I' — or, [pursues] the question 'Who am I?' — can come to know the entire world.
While there are, in creation and in the world, matters worth knowing that are truly infinite, what need is there to know specifically about this 'I'? Could one not instead try to know the world? Or examine the jīva in order to know it? Or inquire concerning God? While the world, the jīva, and Paramātma are all great matters occupying a primary place, what use is there in setting all these aside and, instead, striving to know this common word 'I,' which even innocent little children use again and again in daily life — what fruit could come of that? one may well wonder. The word itself may be ordinary, but the meaning within it is infinite and undivided. That is precisely why every great soul says the very same thing: 'Inquire into yourself, know yourself — only then does liberation come.' Such is the beneficial counsel they give. The scriptures give this very warning. Going by injunctions such as 'That by knowing which everything becomes known,' it becomes clear that inquiry into the Ātma alone is what truly matters. The mahāvākya 'Tattvamasi' teaches that you yourself are this very Ātma. Therefore, in order for your aspiration to be fulfilled, inquire into yourself. 'You' are eternal — so declaring, the scriptures dispel the ignorance that has enveloped you and bring your own essential nature to direct experience, causing it to dawn within you. For one who does not trust the scriptures that have been coming down teaching this supreme