Tacitus: The second heir is always viewed with suspicion and resentment.

Romain Rolland: Doubt can destroy yesterday’s faith and open the way for tomorrow’s faith.

UK: Doubt is the key to knowledge.

UK: What no one suspects needs no confirmation.

Germany: Young people believe many false things, and old people doubt many true things.

Mill: It is doubtful whether all the machines that have been invented have made any reduction in the daily toil of man.

novalis: In order to correctly understand the truth, we must first doubt it and argue with it.

Europe: Hypocrites always doubt the honesty of others.

United States: The most dangerous enemies are those we do not suspect.

UK: A man who knows nothing doubts anything.

Maurice Madan Dugar: Some people are so smart that you wonder what else could interest them.

Unamuno: Real science first teaches people to doubt and to be confused.

Anonymous: The evidence tells us where to focus our suspicion.

Bacon: Poverty of knowledge can make people have many doubts.

Doubt is an element of criticism, and the tendency of criticism must be skeptical.

------Disraeli

Doubt It can destroy yesterday's faith and open the way for tomorrow's faith.

------Romain Rolland

A frank person will never give up frank questions.

------W. Malone

The process of scientific development is a leap starting from curiosity and doubt.

------Ai Yin Stan

Faith and doubt complement each other. Without doubt, there is no true faith.

------Heise