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

You serve me a slice of raw beef, Heliodorus, and pour me out three cups of wine rawer than the beef, and then you wash me out at once with epigrams. – Lucilius, in The Greek Anthology, Volume IV, “Book XI: The Convivial and Satiric

Nevertheless, a maxim does not necessarily become a proverb. Many grubs never grow to butterflies; and a maxim is only a proverb in its caterpillar stage—a candidate for a wider sphere and longer flight than most are destined to attain. – “Proverbs Secular and Sacred,” The North British Review, February 1858