Men will readily enough avow cruelty, passion, even avarice, but never cowardice, because such an admission would bring them, among savages and even in civilized society, into mortal danger.

[Les hommes avouent volontiers la cruauté, la colère, l’avarice même, mais jamais la lâcheté, parce que cet aveu les mettrait, chez les sauvages et même dans une société polie, en un danger mortel.]

Anatole France (1844-1924) French poet, journalist, novelist, Nobel Laureate [pseud. of Jaques-Anatole-François Thibault]

The Gods Will Have Blood [Les Dieux Ont Soif], ch. 19 [Brotteaux] (1912) [tr. Allinson (1913), The Gods Are Athirst]
    (Source)

(Source (French)). Alternate translation:

Men willingly post of their cruelty, their anger, their greed even, but never of their cowardice, because to admit such a thing would put them, whether in a primitive or a civilized society, in mortal peril.
[tr. Davies (1979)]