The eternal idea of creation is thus explained by S. Thomas, Summa, p. i. quæst. xv. art. 1 (Utrum ideæ sint):
“I answer that it is necessary to suppose ideas in the mind of God. Idea is a Greek word, and answers to the Latin forma, form. Whence by the term ideas we understand the forms of things that exist external (præter) to the things themselves. The form of a thing existing external to it may serve two purposes: 1. That it should be the exemplar (ideal) of that of which it is said to be the form, or that it should be, as it were, the principle of knowledge itself, according to which the forms of things that may be known are said to exist in the understanding. And in either point of view it is necessary to suppose ideas, as will be at once manifest. In all things that are not generated by chance, it is necessary that the production of some form should be the result of the act of generation. For an agent would not act with reference to a particular form, except so far as he was already in possession of the likeness of the form in question. In some agents the form of the thing to be produced already pre-exists in a natural manner (secundum esse naturale), as in those things which act by natural laws; but in others the form pre-exists in the intellect (secundum esse intelligibile). Thus the likeness or form of a house already exists in the mind of the builder, and this may be called the idea of a house; for the architect intends to make the house resemble the form which he has conceived in his mind. As, then, the world is not made by chance, it follows that there must exist a form (idea) in the mind of God, after the likeness of which the world was made.”
Quite similar to these words of S. Thomas are the statements of S. Augustine, Dionysius, and other fathers, who had to deal on the one hand with the philosophy of Plato, which taught that God created the world out of eternal matter, and according to an exemplar or ideal existing externally to himself (κοσμος νοητος); and on the other with the Gnostic Pantheism, which taught that the divine idea after which the world was created was identical with God, and creation consequently no more than an extension or manifestation of the Godhead.
Similar also is the following passage of the Abate Rosmini:
“‘Fide intelligimus aptata esse secula verbo Dei, ut ex invisibilibus visibilia fierent’ (Heb. xi. 3). What ever are these invisible things from which the things that are visible have been drawn? They are the conceptions of the Almighty, which subsisted in his mind before the creation of the universe; they are the decrees which he has framed from all eternity, but which remained invisible to all creatures, because these latter were not yet formed and the former not yet carried into execution. These decrees and conceptions are the design of the wise Architect, according to which the building has to be formed. But this design was never at any time drawn out on any external material, on paper or stone, but existed only in his own mind” (Rosmini, Della Divina Providenza, ed. Milano, 1846, p. 57).
Creation proceeds from the thought and will of God jointly exercised, and is something external to God, which he has brought into being out of absolute nothing, to quote Professor Staudenmaier: “The world is God’s idea of the world brought into being, and the perfection of the original world consisted in the fact that it absolutely corresponded to the divine idea” (Die Lehre von der Idee, p. 914). “Et vidit Deus quod esset bonum” (Gen. i. 10).
The creation which we see, and of which we are ourselves immediately a part, bears the appearance of being an organized system, far outreaching the powers of our intelligence; and we conclude intuitively that not only as an organized whole it answers to the idea of God, which contemplated system, order, harmony, and subordination of parts, but, further, that every several part, as it came forth from the hand of the Creator, was found good. In creation there are two principal parts, the material world and the world of spirits. Matter, from the first instant of creation, being without free will or mind, necessarily obeys the laws of its Creator, and at once absolutely answers to the divine idea. But spirits were created in the image of God, and were endowed with the likeness of his power of thought and will, and with a personality resulting from the possession of these gifts. To them, therefore, there is a moral trial or probation to be passed through before they finally correspond to the idea of their Creator. It is indeed true that from the instant of their creation they realize the divine idea, in so far as that idea contemplates them, about to enter upon probation; but their passing through this trial or probation to the attainment of their perfection is also contemplated, and of this perfection the divine idea is the exemplar or form.
Spirits, then, formed in the image of God, and endowed with created being, intellect, and will, in the present system of creation, pass through probation; and their probation consists in learning to possess these gifts in subordination to their Creator, who is absolute being, intellect, and will; and this trial is necessary to the perfection of their nature and to their passing into the possession of their permanent place (ταξις) in the great order and harmony of the universe. There is not, and cannot be, in the mind of God, any idea of evil. Evil has its sole origin in the rebellion of the created spirit when it refuses to possess and use its power of thought and will in subordination to the law and majesty of its Creator. And hence, although the rebel spirit answered equally with others at the first moment of its creation to the divine idea, yet, inasmuch as in its subsequent career it has placed itself against its Creator, it has ceased to answer to the divine idea; it has become a contradiction to it, and henceforward its existence is evil.
The case as regards the human creation does not differ at all in principle. Man is also a spirit, though his spirit be united to a body, and he is possessed of the same trinity of gifts—being, thought, and will—although from the circumstance of his coming into the world in the form of an infant, with his intellect and will in a state of germ, appointed to acquire their natural maturity only in process of time, his probation would seem to require a longer period than that of the angels, and to be subject to the fluctuation of rebellions, succeeded by repentances, and vice versâ—all which hardly seems probable in their case. Still man, like the angels, passes through his probation; and when he has passed through it, he is found either realizing the idea of his Creator, and happy, or fallen from it, and henceforward in contradiction with it, for an eternity of misery. The idea of the Creator is to man, as well as to the angels, the exemplar, or pattern, of his perfection.
Analogous to the first creation of the world is the second great work of God—the redemption or new creation. Its decree is from God the Father; the carrying into effect the Father’s decree is the work of God the Eternal Son; and the conducting it to perfection during the period of its growth and probation is the work of the Holy Ghost.