“It is difficulties that show what men are.”

Of Inconsistency, Chap. xxi.
Bartlett's Familiar Quotations, 10th ed. (1919)

The Tragic Sense of Life (1913), IV : The Essence of Catholicism
Context: And why be scandalized by the infallibility of a man, of the Pope? What difference does it make whether it be a book that is infallible — the Bible, or a society of men — the Church, or a single man? Does it make any essential change in the rational difficulty? And since the infallibility of a book or of a society of men is not more rational than that of a single man, this supreme offense to the eyes of reason has to be postulated.

Source: A History of Economic Thought (1939), Chapter V, Reaction And Revolution, p. 220

Source: Antifragile: Things That Gain from Disorder

Source: 1930s-1951, Philosophical Occasions 1912-1951 (1993), Ch. 9 : Philosophy (chapters 86–93 of the so called Big Typescript), p. 161
Corresponding to TS 213, Kapitel 86
Context: What makes a subject difficult to understand — if it is significant, important — is not that some special instruction about abstruse things is necessary to understand it. Rather it is the contrast between the understanding of the subject and what most people want to see. Because of this the very things that are most obvious can become the most difficult to understand. What has to be overcome is not difficulty of the intellect but of the will. [Nicht eine Schwierigkeit des Verstandes, sondern des Willens ist zu überwinden. ]

Source: Pensées

Of Agesilaus the Great
Laconic Apophthegms

Source: The Curse of the Pharaohs