Source of Doubt

The doubts of the sadhaks more often rise from the vital than from the true mental—when the vital goes wrong or is in trouble or depression, the doubts rise and repeat themselves in the same form and the same language, no matter how much the mind had been convinced by either patent proofs or intellectual answers. I have noticed that always the vital is irrational (even when it uses the reason to justify itself) and it believes or disbelieves according to its feeling, not according to reason.

Ref : Letters on Yoga Vol. III