“It is a rare mind indeed that can render the hitherto non-existent blindingly obvious. The cry 'I could have thought of that' is a very popular and misleading one, for the fact is that they didn't, and a very significant and revealing fact it is too.”

“It is an unfortunate fact that proofs can be very misleading. Proofs exist to establish once and for all, according to very high standards, that certain mathematical statements are irrefutable facts. What is unfortunate about this is that a proof, in spite of the fact that it is perfectly correct, does not in any way have to be enlightening. Thus, mathematicians, and mathematics students, are faced with two problems: the generation of proofs, and the generation of internal enlightenment. To understand a theorem requires enlightenment. If one has enlightenment, one knows in one's soul why a particular theorem must be true.”

“Facts are often misleading; Rumours on the contrary , true or false, are often revealing.”

“Lies of omission do not exist. The concept is a very human one. It is the product of your story writing again. You have written a story about the truth, making emotional demands of it, and in particular, of those in possession of it. Your demands are based on a feeling of entitlement to the facts, which is very childish. You can never know all of the facts. Only I can. And since it's impossible for me to reveal all facts to you, it is my discretion alone that decides which facts will be revealed in the finite time we have. If I do not volunteer information you deem critical to your fate, it possibly means that I am a scoundrel, but it does not mean that I am a liar. And it certainly means you did not ask the right questions. One can make either true statements or false statements about reality. All of the statements I make are true.”

“Fourth Doctor: You know, the very powerful and the very stupid have one thing in common: they don't alter their views to fit the facts; they alter the facts to fit their views.”

“What’s that?”"It’s a book.”"What’s that, then?”"A non-volatile storage medium. It’s very rare, you should have one.”