“You'd have to be dead not to be impressed by his sincerity. But then didn't Oscar Wilde say say "The worst vice of the fanatic is his sincerity."”

Source: Academy Series - Priscilla "Hutch" Hutchins, Odyssey (2006), Chapter 3 (p. 24)

1840s, Heroes and Hero-Worship (1840), The Hero as Prophet

Nature's Nobleman (1844)
Context: His fashion is passion, sincere and intense, —
His impulse is simple and true;
Yet temper'd by judgment, and taught by good sense,
And cordial with me and with you.

The Analects, The Doctrine of the Mean
Context: Earnest in practicing the ordinary virtues, and careful in speaking about them, if, in his practice, he has anything defective, the superior man dares not but exert himself; and if, in his words, he has any excess, he dares not allow himself such license. Thus his words have respect to his actions, and his actions have respect to his words; is it not just an entire sincerity which marks the superior man?

O encontro marcado [A Time to Meet] (1956), trans. John Procter, p. 210

Un homme se définit aussi bien par ses comédies que par ses élans sincères.
http://books.google.com/books?id=9FgoAQAAIAAJ&q=%22un+homme+se+d%C3%A9finit+aussi+bien+par+ses+com%C3%A9dies+que+par+ses+%C3%A9lans+sinc%C3%A8res%22&pg=PA25#v=onepage
The Myth of Sisyphus (1942), An Absurd Reasoning

Source: The Mortdecai Trilogy, Don't Point That Thing At Me (1972), Ch. 1.

precedes by twelve years Truman Capote’s putdown of Jack Kerouac: “That isn’t writing at all, it’s typing.”; “from Verse Chronicle”, p. 137
Kipling, Auden & Co: Essays and Reviews 1935-1964 (1980)

Autobiography of a Yogi (1946)