What does this quote mean?

“Three may keep a secret, if two of them are dead.”

The joke exaggerates how difficult secrecy becomes once information is shared, making discretion the safest form of confidentiality.

Source note: Poor Richard’s Almanack; one of Franklin’s compact maxims about secrecy and human behavior.

“Selfishness must always be forgiven you know, because there is no hope of a cure.”

The line is comic rather than literal advice, using exaggeration to expose how readily people excuse entrenched self-interest.

Source note: Mary Crawford makes the remark while discussing motives and conduct in company.

“The gentle reader will never, never know what a consummate ass he can become, until he goes abroad.”

The joke turns travel into a mirror for vanity: unfamiliar settings can expose affectation and foolishness that remain easier to overlook at home.

Source note: The Innocents Abroad, chapter on travelers adopting foreign fashions; this is Twain’s comic first-person travel narration rather than a literal rule about every traveler.

“We’re all mad here.”

The Cheshire Cat turns abnormality into a shared condition, humorously questioning who gets to define what counts as normal.

Source note: Alice’s Adventures in Wonderland, Chapter 6.

“Brevity is the soul of wit.”

The line praises compression: saying less can sharpen meaning when the words that remain do real work.

Source note: Hamlet, Act 2, Scene 2; Polonius says this while promising the King and Queen he will be brief, immediately before continuing at comic length. The dramatic irony is part of the line’s context.

“To err is human; to forgive, divine.”

Error is treated as ordinary human limitation, while forgiveness requires an additional act of generosity.

Source note: An Essay on Criticism, Part II; Pope warns that shallow learning can produce premature confidence before deeper study tempers judgment.