Not everything that can be extracted appears in anthologies of quotations, in commonplace books, or on the back of Celestial Seasonings boxes. Only certain sorts of extracts become quotations. – Gary Saul Morson, The Words of Others: From Quotations to Culture, 2011

The hunter for aphorisms on human nature has to fish in muddy water, and he is even condemned to find much of his own mind. – Francis H. Bradley, Aphorisms, 1930

Then your words of abuse today may turn into a universally valid principle of denigration, for words are magical formulae. They leave fingermarks behind on the brain, which in the twinkling of an eye becomes the footprints of history. One ought to watch one’s every word. – Franz Kafka, quoted by Gustav Janouch, Conversations with Kafka