“Imaginary evil is romantic and varied; real evil is gloomy, monotonous, barren, boring. Imaginary good is boring; real good is always new, marvelous, intoxicating.”

4 August 1796
1750s, Diaries (1750s-1790s)

Commenting on her novel The Group. New York Herald Tribune (5 January 1964)

Source: Red Mars (1992), Chapter 6, “Guns Under the Table” (p. 460)

The Captive Mind (1953)
Context: Whoever saw, as many did, a whole city reduced to rubble — kilometers of streets on which there remained no trace of life, not even a cat, not even a homeless dog — emerged with a rather ironic attitude toward descriptions of the hell of the big city by contemporary poets, descriptions of the hell in their own souls. A real "wasteland" is much more terrible than any imaginary one. Whoever has not dwelt in the midst of horror and dread cannot know how strongly a witness and participant protests against himself, against his own neglect and egoism. Destruction and suffering are the school of social thought.

The Universe in a Nutshell (2001), p. 59
Context: One might think this means that imaginary numbers are just a mathematical game having nothing to do with the real world. From the viewpoint of positivist philosophy, however, one cannot determine what is real. All one can do is find which mathematical models describe the universe we live in. It turns out that a mathematical model involving imaginary time predicts not only effects we have already observed but also effects we have not been able to measure yet nevertheless believe in for other reasons. So what is real and what is imaginary? Is the distinction just in our minds?

infinity plus interview (2001)
Variant: In real life, the hardest aspect of the battle between good and evil is determining which is which.
Context: The battle between good and evil is a legitimate theme for a Fantasy (or for any work of fiction, for that matter), but in real life that battle is fought chiefly in the individual human heart. Too many contemporary Fantasies take the easy way out by externalizing the struggle, so the heroic protagonists need only smite the evil minions of the dark power to win the day. And you can tell the evil minions, because they're inevitably ugly and they all wear black.
I wanted to stand much of that on its head.
In real life, the hardest aspect of the battle between good and evil is determining which is which.