All doubts will cease only when the doubter and his source has been found. There is no
use removing doubts one by one. If we clear one doubt, another doubt will arise and there
will be no end of doubts. But if, by seeking the source of the doubter, the doubter is found to
be really non-existent, then all doubts will cease.

~ Sri Ramana Maharshi

If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainties.

~ Francis Bacon

Where there is great doubt, there will be great awakening; small doubt, small awakening, no doubt, no awakening.

~ Zen Proverb

When you are deluded and full of doubt, even a thousand books of scripture are not enough. When you have realized understanding, even one word is too much.

~ Fen-Yang

Doubt transports you to the truth. Who does not doubt fails to inquire. Who does not inquire fails to gain insight. Without insight, you remain blind and perplexed.

~ Al-Ghazali, Sufi master (1058-1111)

"Doubt grows with knowledge."
- Goethe