“All intelligent thoughts have already been thought; what is necessary is only to try to think them again.”

“All truly wise thoughts have been thought already thousands of times; but to make them truly ours, we must think them over again honestly, until they take root in our personal experience.”

“Think and then think what you have thought. Is it really what you had thought. Think again.”

“As long as there have been men and they have lived, they have all felt this tragic ambiguity of their condition, but as long as there have been philosophers and they have thought, most of them have tried to mask it.”

“I think it is the duty of all human beings, as intelligent and communicative beings, to learn all the ideas thought up before ours and use them as a means to think up new ones.”

“First Thoughts are the everyday thoughts. Everyone has those. Second Thoughts are the thoughts you think about the way you think. People who enjoy thinking have those. Third Thoughts are thoughts that watch the world and think all by themselves. They’re rare, and often troublesome. Listening to them is part of witchcraft.”