“Good humor is the health of the soul, sadness its poison. ”

The Bonehunters (2006)
Context: So much had changed inside him. He was no believer in causes, not any more. Certainty was an illusion, a lie. Fanaticism was poison in the soul, and the first victim in its inexorable, ever-growing list was compassion. Who could speak of freedom, when one's soul was bound in chains?

Source: Gardens of the Moon (1999), Chapter 4 (p. 153)

Stoicorum veterum fragmenta, fragment 359

Source: Spoon River Anthology

As quoted in Epistulae morales ad Lucilium by Seneca, Epistle LXXXVII (trans. R. M. Gummere)

What I Saw at the Revolution : A Political Life in the Reagan Era (1990), p. 179
Context: Wit penetrates; humor envelops. Wit is a function of verbal intelligence; humor is imagination operating on good nature. John Kennedy had wit, and so did Lincoln, who also had abundant humor; Reagan was mostly humor.

Source: The Thin Red Line

Books, Shock Value: A Tasteful Book About Bad Taste (1981)