“First time's a fluke; second time's a coincidence," said Velius.
"Third time's tradition," finished Erik.”

Saying 140

Source: Along for the Ride

Variant: Mr Bond, they have a saying in Chicago: 'Once is happenstance. Twice is coincidence. The third time it's enemy action'.
Source: Auric Goldfinger, Ch. 14 : Things That Go Thump In The Night

Source: So Long, and Thanks for All the Fish

Xfm 07 December 2002
On The Elephant Man

Address at Bennington College (30 October 1984) as published in "Reflections of a Writer: Long Work, Short Life" in The New York Times (20 March 1988)
Context: I have written almost all my life. My writing has drawn, out of a reluctant soul, a measure of astonishment at the nature of life. And the more I wrote well, the better I felt I had to write.
In writing I had to say what had happened to me, yet present it as though it had been magically revealed. I began to write seriously when I had taught myself the discipline necessary to achieve what I wanted. When I touched that time, my words announced themselves to me. I have given my life to writing without regret, except when I consider what in my work I might have done better. I wanted my writing to be as good as it must be, and on the whole I think it is. I would write a book, or a short story, at least three times — once to understand it, the second time to improve the prose, and a third to compel it to say what it still must say.
Somewhere I put it this way: first drafts are for learning what one's fiction wants him to say. Revision works with that knowledge to enlarge and enhance an idea, to re-form it. Revision is one of the exquisite pleasures of writing: The men and things of today are wont to lie fairer and truer in tomorrow's meadow, Henry Thoreau said.
I don't regret the years I put into my work. Perhaps I regret the fact that I was not two men, one who could live a full life apart from writing; and one who lived in art, exploring all he had to experience and know how to make his work right; yet not regretting that he had put his life into the art of perfecting the work.

As quoted in: J.Muller, Physical Chemistry in Depth (Springer Science & Business Media, 1992), p. 1. No primary source is given in that book.
Disputed

Source: Keeping the Moon

as quoted by [Steven Chu and Charles H. Townes, Biographical Memoirs V.83, National Academies Press, 2003, 0-309-08699-X, 201]