Metaphysics; the art of disputation; that strictly logical discussion which leads to reliable results. The product or result is ideas, which, being classified, produce knowledge; but all knowledge being of the divine types, must conduce more or less to practical results and good morals. (Greek, dia-lego, to speak thoroughly.)
Kant used the word to signify the theory of fallacies, and Hegel for that concept which of necessity develops its opposite.
The following questions from John of Salisbury are fair specimens of the Middle-age subjects of discussion : -
(1) When a person buys a whole cloak, does the cowl belong to his purchase?
(2) When a hog is driven to market with a rope round its neck, does the man or the rope take him?
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894