If I am fool it is at least a doubting one and I envy no one the certainty of his self-approved wisdom.

It is by doubting that we come to investigate and by investigating that we recognize the truth.

The key to wisdom is this - constant and frequent questioning for by doubting we are led to question and by questioning we arrive at the truth.

A man desires praise that he may be reassured that he may be quit of his doubting of himself he is indifferent to applause when he is confident of success.

Science we are repeatedly told is the most reliable form of knowledge about the world because it is based on testable hypotheses. Religion by contrast is based on faith. The term 'doubting Thomas' well illustrates the difference.

I forbid you agnostic doubting thoughts to destroy the house of my faith.

Deep into that darkness peering long I stood there wondering fearing doubting dreaming dreams no mortal ever dared to dream before.