The obstinacy of cleverness and reason is nothing to the obstinacy of folly and inanity.
Harriet Beecher Stowe
It may be the part of a friend to rebuke a friend's folly.
J. R. R. Tolkien
For the subtlest folly proceeds from the subtlest wisdom.
John Webster
If the fool would persist in his folly he would become wise.
William Blake
The fool who persists in his folly will become wise.
Folly loves the martyrdom of fame.
Lord Byron
His foe was folly and his weapon wit.
Anthony Hope