“Man can learn nothing except by going from the known to the unknown.”
“The most crucial problem with intellectual learning is that it receives the unknown on the grounds of the known.”
“Only the unknown frightens men. But once a man has faced the unknown, that terror becomes the known.”
“Whenever we proceed from the known into the unknown we may hope to understand, but we may have to learn at the same time a new meaning of the word 'understanding.”
“For once a thing is known, it can never be unknown. It can only be forgotten.”
“You can learn to find unknowns in equations, draw equidistant lines and demonstrate theorems, but in real life there's nothing to position, calculate, or guess.”