We are born questioners. Look at the wonderment of a little child in its eyes before it can speak. The child's great word when it begins to speak is "why." Every child is full of every kind of question, about every kind of thing that moves, and shines, and changes, in the little world in which it lives. That is the incipient doubt in the nature of man. Respect doubt for its origin. It is an inevitable thing. It is not a thing to be crushed. It is a part of man as God made him. ... Doubt is the prelude of knowledge.