“The Church no longer contends that knowledge is in itself sinful, though it did so in its palmy days; but the acquisition of knowledge, even though not sinful, is dangerous, since it may lead to pride of intellect, and hence to a questioning of the Christian dogma.”

“I do not pretend to be able to prove that there is no God. I equally cannot prove that Satan is a fiction. The Christian god may exist; so may the gods of Olympus, or of ancient Egypt, or of Babylon. But no one of these hypotheses is more probable than any other: they lie outside the region of even probable knowledge, and therefore there is no reason to consider any of them.”

“Since all terms that are defined are defined by means of other terms, it is clear that human knowledge must always be content to accept some terms as intelligible without definition, in order to have a starting point for its definitions...[and] since human powers are finite, the definitions known to us must always begin somewhere, with terms undefined for the moment, though perhaps not permanently." - Introduction to Mathematical Philosophy”

“Many orthodox people speak as though it were the business of sceptics to disprove received dogmas rather than of dogmatists to prove them.”

“Science may set limits to knowledge, but should not set limits to imagination.”

“We shall be compelled to renounce the hope of finding philosophical proofs of religious beliefs. ...Hence, once more, the value of philosophy must not depend upon any supposed body of definitely ascertainable knowledge to be acquired by those who study it.”

“Is there any knowledge in the world which is so certain that no reasonable man could doubt it?”