The reason of God contemplates and comprehends the exemplars or original models of all natural forms, whatever they may be; for visible things are only fleeting shadows, quickly passing away; ideas or exemplars are everlasting. With so much power did he set forth this theory of ideas, and, it must be added, with so much obscurity, that some have asserted his belief in an extramundane space in which exist incorporeal beings, the ideas or original exemplars of all organic and inorganic forms. An illustration may remove some of the obscurity of these views. Thus all men, though they may present different appearances when compared with each other, are obviously fashioned upon the same model, to which they all more or less perfectly conform. All trees of the same kind, though they may differ from one another, are, in like manner, fashioned upon a common model, to which they more or less perfectly conform. To such models, exemplars, or types, Plato gave the designation of Ideas. Our knowledge thereof is clearly not obtained from the senses, but from reflection. Now Plato asserted that these ideas are not only conceptions of the mind, but actually perceptions or entities having a real existence; nay, more, that they are the only real existences. Objects are thus only material embodiments of ideas, and in representation are not exact; for correspondence between an object and its model is only so far as circumstances will permit. Hence we can never determine all the properties or functions of the idea from an examination of its imperfect material representation, any more than we can discover the character or qualities of a man from pictures of him, no matter how excellent those pictures may be. [Sidenote: Doctrine of Reminiscence.] [Sidenote: Recollections during transmigration.]