“Socratic trustworthiness depends upon devices of irony, both spoken and acted. … The irony of words prevents Socrates from being taken as the source of doctrines. The irony of actions prevents Socrates from being made into the literal founder of a philosophic school. … The ironic voice does not seek to possess the student, but directs him, lustlessly, to the desire of philosophy itself.”

trans. Michael Chase (1995), p. 156
La Philosophie comme manière de vivre (2001)

1840s, On the Concept of Irony with Continual Reference to Socrates (1841)

Source: Nietzsche: Life as Literature (1985), p. 26.

Essay 3, Aphorism 7
On the Genealogy of Morality (1887)

All and Everything: Views from the Real World (1973)
Context: There do exist enquiring minds, which long for the truth of the heart, seek it, strive to solve the problems set by life, try to penetrate to the essence of things and phenomena and to penetrate into themselves. If a man reasons and thinks soundly, no matter which path he follows in solving these problems, he must inevitably arrive back at himself, and begin with the solution of the problem of what he is himself and what his place is in the world around him. For without this knowledge, he will have no focal point in his search. Socrates’ words, “Know thyself” remain for all those who seek true knowledge and being.

Source: The Screaming Staircase

Source: The Magic Mountain (1924), Ch. 5
Context: Irony, forsooth! Guard yourself, Engineer, from the sort of irony that thrives up here; guard yourself altogether from taking on their mental attitude! Where irony is not a direct and classic device of oratory, not for a moment equivocal to a healthy mind, it makes for depravity, it becomes a drawback to civilization, an unclean traffic with the forces of reaction, vice and materialism.

Alcibiades I

Source: 1840s, On the Concept of Irony with Continual Reference to Socrates (1841), p. 173