“Short on glamour and long on tragedy.”

As quoted in his obituary in The Guardian (28 December 1977)

Source: The Happiness Project: Or Why I Spent a Year Trying to Sing in the Morning, Clean My Closets, Fight Right, Read Aristotle, and Generally Have More Fun

Seneca's (De Brevitate Vitae, 1.1) Latin translation of the Greek by Hippocrates.
Misattributed

Part of the secret "call and response" codewords by which members of the long-lived Howard Families can identify others:
: Life is short.
But the years are long.
Not while the evil days come not.
Methuselah's Children (1958)

Letter to Harrison Blake (16 November 1857)
Context: Let me suggest a theme for you: to state to yourself precisely and completely what that walk over the mountains amounted to for you, — returning to this essay again and again, until you are satisfied that all that was important in your experience is in it. Give this good reason to yourself for having gone over the mountains, for mankind is ever going over a mountain. Don't suppose that you can tell it precisely the first dozen times you try, but at 'em again, especially when, after a sufficient pause, you suspect that you are touching the heart or summit of the matter, reiterate your blows there, and account for the mountain to yourself. Not that the story need be long, but it will take a long while to make it short.

Source: Book 3, Chapter 6 “The God Feasters” (p. 139), Corum, The Knight of the Swords (1971)

Source: Lady Midnight