That leads us to the next point, the relation of God without to God within. To the yogi, who is the very type of Hindu thought, there is no definite proof of God save the witness of the Self within to His existence, and his idea of finding the proof of God is that you should strip away from your consciousness all limitations, and thus reach the stage where you have pure consciousness–save a veil of the thin nirvanic matter.
Then you know that God is. So you read in the Upanishad: “Whose only proof is the witness of the Self.” This is very different from Western methods of thought, which try to demonstrate God by a process of argument.
The Hindu will tell you that you cannot demonstrate God by any argument or reasoning; He is above and beyond reasoning, and although the reason may guide you on the way, it will not prove to demonstration that God is. The only way you can know Him is by diving into yourself.
There you will find Him, and know that He is without as well as within you; and Yoga is a system that enables you to get rid of everything from consciousness that is not God, save that one veil of the nirvanic atom, and so to know that God is, with an unshakable certainty of conviction. To the Hindu that inner conviction is the only thing worthy to be called faith, and this gives you the reason why faith is said to be beyond reason, and so is often confused with credulity. Faith is beyond reason, because it is the testimony of the Self to himself, that conviction of existence as Self, of which reason is only one of the outer manifestations; and the only true faith is that inner conviction, which no argument can either strengthen or weaken, of the innermost Self of you, that of which alone you are entirely sure.
It is the aim of Yoga to enable you to reach that Self constantly not by a sudden glimpse of intuition, but steadily, unshakably, and unchangeably, and when that Self is reached, then the question: “Is there a God?” can never again come into the. human mind.