“The most necessary learning is that which unlearns evil. ”

§ 4
From Lives and Opinions of the Eminent Philosophers by Diogenes Laërtius

§ 7
From Lives and Opinions of the Eminent Philosophers by Diogenes Laërtius

Source: Losing My Virginity: How I've Survived, Had Fun, and Made a Fortune Doing Business My Way

"Fall of a City"
Selected Poems (1941)
Context: All the lessons learned, unlearned;
The young, who learned to read, now blind
Their eyes with an archaic film;
The peasant relapses to a stumbling tune
Following the donkey`s bray;
These only remember to forget. But somewhere some word presses
On the high door of a skull and in some corner
Of an irrefrangible eye
Some old man memory jumps to a child
— Spark from the days of energy.
And the child hoards it like a bitter toy.

The Ringworld Throne (1996)

Introductio ad prudentiam: Part II (1727), Gnomologia (1732)

Post-Presidency, Nobel lecture (2002)
Source: The Nobel Peace Prize Lecture