Both must move ever onward in life, to and fro, like breathing in and breathing out. Whoever makes it a rule to test action by thought, thought by action, cannot falter, and if he does, will soon find his way back to the right road. Truth is a torch but a tremendous one. That is why we hurry past it, shielding our eyes, indeed, in fear of getting burned. We cannot possess what we do not understand.
Hypotheses are lullabies for teachers to sing their students to sleep.
The close and thoughtful observer more and more learns to recognize his limitations. He realizes that with the steady growth of knowledge more and more new problems keep on emerging. The first and last thing required of genius is the love of truth. Once you have missed the first buttonhole you'll never manage to button up. The thinker makes a great mistake when he asks after cause and effect.