This is the Platonic proof. Plato recognized the principle of substance (οὐσία--ὑποκείµενον), and therefore he proceeds in the "Timæus" to inquire for the real ground of all existence; and in the "Republic," for the real ground of all truth and certitude.
The universe consists of two parts, permanent existences and transient phenomena--being and genesis; the one eternally constant, the other mutable and subject to change; the former apprehended by the reason, the latter perceived by sense. For each of these there must be a principle, subject, or substratum--a principle or subject-matter, which is the ground or condition of the sensible world, and a principle or substance, which is the ground and reason of the intelligible world or world of ideas. The subject-matter, or ground of the sensible world, is "the receptacle" and "nurse" of forms, an "invisible species and formless receiver (which is not earth, or air, or fire, or water) which receives the immanence of the intelligible." [896] The subject or ground of the intelligible world is that in which ideal forms, or eternal archetypes inhere, and which impresses form upon the transitional element, and fashions the world after its own eternal models. This eternal and immutable substance is God, who created the universe as a copy of the eternal archetypes--the everlasting thoughts which dwell in his infinite mind.
[Footnote 896: ][ (return) ] "Timæus," ch. xxiv.
These copies of the eternal archetypes or models are perceived by the reason of man in virtue of its participation in the Ultimate Reason. The reason of man is the organ of truth; by an innate and inalienable right, it grasps unseen and eternal realities. The essence of the soul is akin to that which is real, permanent, and eternal;--It is the offspring and image of God; therefore it has a true communion with the realities of things, by virtue of this kindred and homogeneous nature. It can, therefore, ascend from the universal and necessary ideas, which are apprehended by the reason, to the absolute and supreme Idea, which is the attribute and perfection of God. When the human mind has contemplated any object of beauty, any fact of order, proportion, harmony, and excellency, it may rise to the notion of a quality common to all objects of beauty--from a single beautiful body to two, from two to all others; from beautiful bodies to beautiful sentiments, from beautiful sentiments to beautiful thoughts, until, from thought to thought, we arrive at the highest thought, which has no other object than the perfect, absolute, Divine Beauty. [897] When a man has, from the contemplation of instances of virtue, risen to the notion of a quality common to all these instances, this quality becomes the representative of an ineffable something which, in the sphere of immutable reality, answers to the conception in his soul. "At the extreme limits of the intellectual world is the Idea of the Good, which is perceived with difficulty, but, in fine, can not be perceived without concluding that it is the source of all that is beautiful and good; that in the visible world it produces light, and the star whence light directly comes; that in the invisible world it directly produces truth and intelligence." [898] This absolute Good is God.
[Footnote 897: ][ (return) ] "Banquet," § 34.
[Footnote 898: ][ (return) ] "Republic," bk. vii. ch. iii.
The order in which these several methods of proof were developed, will at once present itself to the mind of the reader as the natural order of thought. The first and most obvious aspect which nature presents to the opening mind is that of movement and change--a succession of phenomena suggesting the idea of power. Secondly, a closer attention reveals a resemblance of phenomena among themselves, a uniformity of nature--an order, proportion, and harmony pervading the cosmos, which suggest an identity and unity of power and of reason, pervading and controlling all things. Thirdly, a still closer inspection of nature reveals a wonderful adaptation of means to the fulfillment of special ends, of organs designed to fulfill specific functions, suggesting the idea of purpose, contrivance, and choice, and indicating that the power which moves and determines the universe is a personal, thinking, and voluntary agent. And fourthly, a profounder study of the nature of thought, an analysis of personal consciousness, reveals that there are necessary principles, ideas, and laws, which universally govern and determine thought to definite and immovable conceptions--as, for example, the principles of causality, of substance, of identity or unity, of order, of intentionality; and that it is only under these laws that we can conceive the universe. By the law of substance we are compelled to regard these ideas, which are not only laws of thought but also of things, as inherent in a subject, or Being, who made all things, and whose ideas are reflected in the reason of man. Thus from universal and necessary ideas we rise to the absolute Idea, from immutable principles to a First Principle of all principles, a First Thought of all thoughts--that is, to God. This is the history of the development of thought in the individual, and in the race--cause, order, design, idea, being, GOD.