chain of being

In metaphysics, an ancient principle with many variations, originating in neo-Platonism. Essentially, the principle asserts the unity, continuity, and perfection of the universe. The principle assumes that the universe is a hierarchy of different grades of beings – the higher grades of beings possessing more reality or perfection than the lower ones. At the top of the hierarchy is the most perfect being of all – God – or, sometimes, the most perfect creature – Man.

One version of the principle is that for the universe to be as perfect as possible, it must contain the greatest possible diversity in the greatest possible profusion compatible with the laws of nature. Another version is that nothing can remain a real but unactualized possibility throughout all time.