“It is the part of cowardice, not of courage, to go and crouch in a hole under a massive tomb, to avoid the blows of fortune.”

Source: The Heroin Diaries: A Year In The Life Of A Shattered Rock Star

As quoted in Think and Grow Rich : A Black Choice (1991) by Dennis Kimbro and Napoleon Hill, p. 104
Context: Many people feel they are powerless to do anything effective with their lives. It takes courage to break out of the settled mold, but most find conformity more comfortable. This is why the opposite of courage in our society is not cowardice, it's conformity.

original version in French: Je vous répéterai ce que je disais naguère à Guillaume Apollinaire: "Je n'ai, pour ma part, jamais évité l'influence des autres, j'aurais considéré cela comme une lâcheté et un manque de sincérité vis-à-vis de moi-même."
'Interview with Henri Matisse' by Jacques Guenne, in 'L'Art Vivant' (15 September 1925)
1920s

The Book of Ammon
Context: Love without courage and wisdom is sentimentality, as with the ordinary church member. Courage without love and wisdom is foolhardiness, as with the ordinary soldier. Wisdom without love and courage is cowardice, as with the ordinary intellectual. Therefore one with love, courage, and wisdom is one in a million who moves the world, as with Jesus, Buddha, and Gandhi.

Source: Cibola Burn (2014), Chapter 39 (p. 400)

Source: Reflections and Maxims (1746), p. 180.