The problem is the midwife, which can help the birth of new ideas. -Socrates

Skepticism is an important part of scientific spirit. -Zhou

Thinking begins with questions and surprises. -Aristotle

Those who have no doubts about reading must be taught to have doubts, but those who have doubts must have no doubts. Only here can they make progress. -Zhu

Ears have no bottom, and they can be heard from morning till night. -Africa

The key to all science is the question mark. -Balzac