Didascalicon, Book II: the sciences, their parts and their discipline
Chapter II. Into what parts philosophy is divided
Philosophy is divided into theoretical, practical, mechanical and logical. These four contain all knowledge. Theoretical is interpreted speculative; the practical, which by another name they call ethical, that is moral, because morals consist in good action; the mechanical, adulterate, because it is occupied with human works; the logical, sermocinal, because it treats of words. The theoretical is divided into theology, mathematics and physics. Boethius makes this division in other words: dividing the theoretical into the intellectible, the intelligible and the natural; by the intellectible signifying theology; by the intelligible, mathematics; by the natural, physics. He then defines the intellectible thus.