principle of plenitude
Name given by Lovejoy to a principle he detected in much Greek and medieval thought, that the existence and abundance of creation must be as great as the possibility of existence, commensurate therefore with an infinite and inexhaustible source. For if such a source could have reason to make any possibility actual, which we know it to have since there is an actual world, then it would have reason to actualize every possibility consistent with its nature. The non-existence of anything that could have existed would argue a niggardliness, or ‘envy’, in the creative principle that could have brought it about. The principle infused many versions of the view that there is a great chain of being, stretching from the lowest invisible worm to the highest seraph (for it also ensures that there are creatures intermediate between us and God); it also infuses the optimistic view, found as late as the 18th and 19th centuries, that the soul will, or at least could, rise through a perpetual progress of degrees of perfection (an idea effectively criticized by the American Samuel Johnson as giving rise to a version of Zeno's paradox). See also Dante, Neoplatonism.