Our use of the phrase 'The Dark Ages' to cover the period from 600 to 1000 marks our undue concentration on Western Europe. [...] From India to Spain, the brilliant civilisation of Islam flourished. What was lost to Christendom at this time was not lost to civilisation, but quite the contrary. [...] To us it seems that West-European civilisation is civilisation, but this is a narrow view.

What we cannot think we cannot think, therefore we also cannot say what we cannot think.

Neither acquiescence in skepticism nor acquiescence in dogma is what education should produce.

Nine-tenths of the appeal of pornography is due to the indecent feelings concerning sex which moralists inculcate in the young; the other tenth is physiological, and will occur in one way or another whatever the state of the law may be.

[Regarding] the convention that clergymen are more virtuous than other men. Any average selection of mankind, set apart and told that it excels the rest in virtue, must tend to sink below the average.

Abstract work, if one wishes to do it well, must be allowed to destroy one's humanity; one raises a monument which is at the same time a tomb, in which, voluntarily, one slowly inters oneself.

It appeared that after first contemplating a book on some subject, and after giving serious preliminary attention to it, I needed a period of subconscious incubation which could not be hurried and was if anything impeded by deliberate thinking.... Having, by a time of very intense concentration, planted the problem in my subconsciousness, it would germinate underground until, suddenly, the solution emerged with a blinding clarity, so that it only remained to write down what happened as if in a revelation.