Men become civilized, not in proportion to their willingness to believe, but in their readiness to doubt.

The great achievement of liberal Protestantism was to make God boring.

Congress consists of one-third, more or less, scoundrels; two-thirds, more or less, idiots; and three-thirds, more or less, poltroons.

[Science] must be amoral by its very nature: The minute it begins separating facts into the two categories of good ones and bad ones it ceases to be science and becomes a mere nuisance, like theology.

There are no dull subjects. There are only dull writers.

The final test of truth is ridicule. Very few dogmas have ever faced it and survived.

I hope I need not confess that a large part of my stock in trade consists of platitudes rescued from the cobwebbed shelves of yesterday... This borrowing and refurbishing of shop-worn goods, as a matter of fact, is the invariable habit of traders in ideas, at all times and everywhere. It is not, however, that all the conceivable human notions have been thought out; it is simply, to be quite honest, that the sort of men who volunteer to think out new ones seldom, if ever, have wind enough for a full day's work.