"My mind is not a repository for other people's garbage."

"The true method of philosophy is to say nothing except what can be said, i.e. propositions of natural science."

"What is good is also divine. Peculiar as it may sound, that sums up my ethics."

"My greatest fear is that I shall not be able to finish my work."

"I am not interested in constructing a building, but in having a clear view of the foundations of possible buildings."