The erroneous belief is the minor problem, the excessive conviction the major one.
Error is boundless.
Nor hope nor doubt,
Though both be groundless,
Will average out.
Y explains X, and Z explains Y, and do not inquire too deeply after Z.
Continuous moral progress of the species is an idea so grotesquely flattering that it cannot possibly be true.
To err is human; when our betters err, not to exult, divine.
Genuine error varies directly with spurious precision.
The one simple thing that will change your life is to stop believing that one simple thing will change your life.
The right side of history — it is a marvel in its way. Five small words, yet is there a contemporary folly it neglects to embrace?
Men prefer disaster to delay.
People will cheerfully confess ignorance of a topic and reject indignantly the suggestion that it might debar them from an opinion.
All metaphors are wrong; some metaphors are useful.