What we know is not capable of being otherwise; of things capable of being otherwise we do not know, when they have passed outside our observation, whether they exist or not. Therefore the object of knowledge is of necessity. Therefore it is eternal; for things that are of necessity in the unqualified sense are all eternal; and things that are eternal are ungenerated and imperishable.
Aristotle (384–323 B.C.), Greek philosopher. Nicomachean Ethics 6.3; 1139b19-25, trans. by Ross-Urmson, The Complete Works of Aristotle, ed. Jonathan Barnes, Princeton, Princeton University Press (1985).