The dominant philosophical principle of Plato is what is known as the Theory of Ideas. He imagined a world of real existences, invisible, incorporeal, eternal, grasped only by thought, prior to the objects of the physical universe, and the models or archetypes of them. In "The Timæus," which is a system of cosmology at once religious and metaphysical, the "Ideas" are represented as the thoughts of the one Supreme Mind, the intermediate powers by which the Supreme Unity, known as the "Idea of the Good," or "the Creator," evolves the material universe. Thus the universe is seen as the manifestation of one Beneficent Spirit, who brings it into existence and rules over it through His "ideal" thoughts. Philo adopts completely and uncritically this theory of transcendental ideas in his philosophical exegesis of the cosmogony in Genesis. "Without an incorporeal archetype God brings no simple thing to fulfilment."[238] There is an idea of stars, of grass, of man, of virtue, of music. And the Platonic conception receives a religious sanction. The ideas are a necessary step between God and the material universe, and those who deny them throw all things into confusion.[239] "God would not touch matter Himself, but He did not grudge a share of His nature to it through His powers, of which the true name is ideas." We have already noticed[240] how ingeniously Philo deduces the Theory of Ideas from the Biblical account of the creation, and associates it with the Hebraic conception of the ministerial Wisdom and Word. He, however, gives a new direction to the Platonic theory, owing to his Hebraic conception of God. The ideas with him are not the thoughts of an impersonal mind, but the emanations of a personal, volitional Deity. Keeping close to Jewish tradition, he says that they are the words of the Deity speaking. As human speech consists of incorporeal ideas, which produce an effect upon the minds of others, so the Divine speech is a pattern of incorporeal ideas which impress themselves upon a formless void, and so create the material world.[241] In this way Philo associates his cosmology with his theology. The creative "Ideas" are equated collectively with the Supreme Logos,[242] individually with the Logoi which represent God's particular activities. Thus the Logos represents the whole ideal or noetic world, "the kingdom of Heaven"; and it is in this metaphysical sense that the Logos is the first creation, "the first-born son of God," prior to the physical universe, which is His grandson. The whole universe is thus seen as the orderly manifestation of one principle. Philo, expanding a favorite image of the Haggadah, illustrates God's creation by the simile of a king founding a city. "He gets to him an architect, who first designs in his mind the parts of the perfect city, and then, looking continually to his model, begins to construct the city of stones and wood. So when God resolved to found the world-city, He first brought its form into mind, and