“To see what is right and not to do it is want of courage.”

E 32
Aphorisms (1765-1799), Notebook E (1775 - 1776)

Source: All-American Girl

Pt. 1, ch. 11
Atticus Finch
Variant: Courage is not a man with a gun in his hand. It's knowing you're licked before you begin but you begin anyway and you see it through no matter what. You rarely win, but sometimes you do.
Source: To Kill a Mockingbird (1962)
Context: I wanted you to see what real courage is, instead of getting the idea that courage is a man with a gun in his hand. It's when you know you're licked before you begin, but you begin anyway and see it through no matter what. You rarely win, but sometimes you do.

Source: The Summer Guest

We The Living (1936)
Source: We The Living Part One Chapter 6

The Analects, Chapter I, Chapter II
Variant: To see what is right, and not to do it, is want of courage or of principle.
Context: To worship to other than one's own ancestral spirits is brown-nosing. If you see what is right and fail to act on it, you lack courage.
Variant To see what is right, and not to do it, is want of courage or of principle.

(zh-TW) 非其鬼而祭之，諂也。見義不為，無勇也。
The Analects, Chapter I, Chapter II