Aristotle

“ For instance, suppose some one, seeing that the moon always has its bright side turned towards the sun, quickly inferred that this was so because the moon receives its light from the sun; or again, seeing someone conversing with a rich man, inferred that he was doing so in order to borrow money ”

“ On seeing the major and minor of the syllogism the sagacious man is able to perceive all the causes or middle terms. Thus: Let A represent ‘having its bright side towards the sun’; B ‘lighted from the sun;’ C ‘the moon.’ Now B, ‘lighted from the sun,’ is true of C, the moon ”

“ On Sagacity Sagacity is a rapid perception of the middle term, or cause, resulting from a consideration of the major and minor terms. Sagacity is a faculty for hitting upon the middle term in an imperceptible moment of time. ”