11. The first of these, the triad, is the offspring of the unit, while the unit is the mother of number itself, and presides over all months, and seasons, and years, and every period of time. It may, indeed, be justly termed the origin, foundation, and principle of all number, and derives its name from its abiding character. For, while every other number is diminished or increased according to the subtraction or addition of others, the unit alone continues fixed and steadfast, abstracted from all multitude and the numbers which are formed from it, and resembling that indivisible essence which is distinct from all things beside, but by virtue of participation in which the nature of all things else subsists.