Self Enquiry is to enquire into your own Self, where the source is from where the enquiry arises. Follow the source and return to that unknown place where it begins.
When you arrive there, then you will know that this is the place which gives you happiness and peace, and makes you keep quiet. And he finds himself there, not by words. By himself, he knows that this is the source of me, and the source of all the beings that appear in the Universe.
The easiest way to return to the source is you look at the mind, that it is not going to be attracted by anything outside, and if you keep quiet, a thought will come: "Where is my source?" Don't go outside, but keep quiet. In this quietness, the mind will automatically return to its source. Having returned there, the mind is lost and there is no mind now to search for the light or wisdom anywhere else, and there will be a tremendous fountain of peace. And all doubts are cleared and he will keep quiet, not by tongue but by his heart. His ego is absolutely finished. This is called peace and returning to the source.
Poonjaji is affectionately referred as ‘papaji’ and was a disciple of Sri Ramana Maharshi