The most fundamental thing is to know oneself: Who am I. And to know oneself means to discover - because you are already there, you are not to be invented. Whatsoever you invent will be a fiction, will not be truth. And how can you delude yourself? Maybe for one day you can delude yourself, for two days, but for how long? Delusions wear out. They cannot remain against reality forever. Reality goes on asserting.
And there are only two kinds of people in the world: the majority consists of those who invent the self, and a very small minority of those who discover the self. And the difference is vast, the difference is tremendous: they are two worlds apart. A Buddha, a Jesus, a Bahaudin, a Rumi, a Mansur - they discover.
What do I mean by discovery? The first thing to remember is that you already have the self. You are. That needs no proof. That is indubitably there, you cannot even doubt it.
The great European philosopher, Descartes, says, "The only indubitable fact about life is that I am."
Only this cannot be doubted; everything else can be doubted. You can doubt the world; it may not be, it may be just a dream, as Hindus say - that it is maya, an illusion, a dream in God's mind.
-Rajneesh