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Twas the saying of an ancient sage that humour was the only test of gravity, and gravity of humour. For a subject which would not bear raillery was suspicious; and a jest which would not bear a serious examination was certainly false wit.

"Characteristics", Letter Concerning Enthusiasm, Part I. Sect. V, as quoted in Hoyt's New Cyclopedia Of Practical Quotations, p. 673-74, 1922.
Twas the saying of an ancient sage that humour was the only test of gravity, and gravity of humour. For a subject which would not bear raillery was suspicious; and a jest which would not bear a serious examination was