“Humor is an excellent method of keeping a tight rein on unproductive displays of emotion.”

Quoted in New York Post (29 February 1960)
Letters and interviews

This is composed of excerpts (with some paraphrasing) from a speech of Cato as reported in Livy's History of Rome, book 34, sections 2-4 http://mcadams.posc.mu.edu/txt/ah/Livy/Livy34.html.
Misattributed

Leslie Berger (January 28, 1982) "A Little Night Humor", The Washington Post, C1.

Source: Mindswap (1966), Chapter 6 (p. 28)

Ch 26
The Bishop Murder Case (1929)

Half-Truths and One-And-A-Half Truths (1976)

The Humanist interview (2012)
Context: There were never that many women stand-up comics in the past because the power to make people laugh is also a power that gets people upset. But the ones who were performing were making jokes on themselves usually and now that’s changed. So there are no rules exactly but I think if you see a whole group of people only being self-deprecating, it’s a problem.
But I have always employed humor, and I think it’s absolutely crucial that we do because, among other things, humor is the only free emotion. I mean, you can compel fear, as we know. You can compel love, actually, if somebody is isolated and dependent — it’s like the Stockholm syndrome. But you can’t compel laughter. It happens when two things come together and make a third unexpectedly. It happens when you learn something, too. I think it was Einstein who said he had to be careful when he shaved because if he thought of something suddenly, he’d laugh and cut himself.
So I think laughter is crucial. Some of the original cultures, like the Dalit and the Native American, don’t separate laughter and seriousness. There’s none of this kind of false Episcopalian solemnity.

Source: Bloodfever