For it is not true, as some treatise-mongers lay down in their systems, of the probity of the speaker, that it contributes nothing to persuasion; but moral character nearly, I may say, carries with it the most sovereign efficacy in making credible.
Humor is the only test of gravity, and gravity of humor; for a subject which will not bear raillery is suspicious, and a jest which will not bear serious examination is false wit.
The same thing may have all the kinds of causes, e.g. the moving cause of a house is the art or the builder, the final cause is the function it fulfils, the matter is earth and stones, and the form is the definitory formula.