1 Objection 1: It seems that there are no ideas. For Dionysius says Div. Nom. vii), that God does not know things by ideas. But ideas are for nothing else except that things may be known through them. Therefore there are no ideas.
1 Ad primum sic proceditur. Videtur quod ideae non sint. Dicit enim Dionysius, VII cap. de Div. Nom., quod Deus non cognoscit res secundum ideam. Sed ideae non ponuntur ad aliud, nisi ut per eas cognoscantur res. Ergo ideae non sunt.
2 Objection 2: Further, God knows all things in Himself, as has been already said Question 14, Article 5). But He does not know Himself through an idea; neither therefore other things.
2 Praeterea, Deus in seipso cognoscit omnia, ut supra dictum est. Sed seipsum non cognoscit per ideam. Ergo nec alia.
3 Objection 3: Further, an idea is considered to be the principle of knowledge and action. But the divine essence is a sufficient principle of knowing and effecting all things. It is not therefore necessary to suppose ideas.
3 Praeterea, idea ponitur ut principium cognoscendi et operandi. Sed essentia divina est sufficiens principium cognoscendi et operandi omnia. Non ergo necesse est ponere ideas.
4 On the contrary, Augustine says Octog. Tri. Quaest. qu. xlvi), Such is the power inherent in ideas, that no one can be wise unless they are understood.
4 Sed contra est quod dicit Augustinus, in libro octoginta trium quaest., tanta vis in ideis constituitur, ut, nisi his intellectis, sapiens esse nemo possit.
5 I answer that, It is necessary to suppose ideas in the divine mind. For the Greek word Idea is in Latin forma. Hence by ideas are understood the forms of things, existing apart from the things themselves. Now the form of anything existing apart from the thing itself can be for one of two ends: either to be the type of that of which it is called the form, or to be the principle of the knowledge of that thing, inasmuch as the forms of things knowable are said to be in him who knows them.
In either case we must suppose ideas, as is clear for the following reason: In all things not generated by chance, the form must be the end of any generation whatsoever. But an agent does not act on account of the form, except in so far as the likeness of the form is in the agent, as may happen in two ways. For in some agents the form of the thing to be made pre-exists according to its natural being, as in those that act by their nature; as a man generates a man, or fire generates fire.
Whereas in other agents the form of the thing to be made pre-exists) according to intelligible being, as in those that act by the intellect; and thus the likeness of a house pre-exists in the mind of the builder. And this may be called the idea of the house, since the builder intends to build his house like to the form conceived in his mind. As then the world was not made by chance, but by God acting by His intellect, as will appear later Question 46, Article 1), there must exist in the divine mind a form to the likeness of which the world was made. And in this the notion of an idea consists.
5 Respondeo dicendum quod necesse est ponere in mente divina ideas. Idea enim Graece, Latine forma dicitur, unde per ideas intelliguntur formae aliarum rerum, praeter ipsas res existentes. Forma autem alicuius rei praeter ipsam existens, ad duo esse potest, vel ut sit exemplar eius cuius dicitur forma; vel ut sit principium cognitionis ipsius, secundum quod formae cognoscibilium dicuntur esse in cognoscente. Et quantum ad utrumque est necesse ponere ideas. Quod sic patet. In omnibus enim quae non a casu generantur, necesse est formam esse finem generationis cuiuscumque. Agens autem non ageret propter formam, nisi inquantum similitudo formae est in ipso. Quod quidem contingit dupliciter. In quibusdam enim agentibus praeexistit forma rei fiendae secundum esse naturale, sicut in his quae agunt per naturam; sicut homo generat hominem, et ignis ignem. In quibusdam vero secundum esse intelligibile, ut in his quae agunt per intellectum; sicut similitudo domus praeexistit in mente aedificatoris. Et haec potest dici idea domus, quia artifex intendit domum assimilare formae quam mente concepit. Quia igitur mundus non est casu factus, sed est factus a Deo per intellectum agente, ut infra patebit, necesse est quod in mente divina sit forma, ad similitudinem cuius mundus est factus. Et in hoc consistit ratio ideae.
6 Reply to Objection 1: God does not understand things according to an idea existing outside Himself. Thus Aristotle Metaph. ix) rejects the opinion of Plato, who held that ideas existed of themselves, and not in the intellect.
6 Ad primum ergo dicendum quod Deus non intelligit res secundum ideam extra se existentem. Et sic etiam Aristoteles improbat opinionem Platonis de ideis, secundum quod ponebat eas per se existentes, non in intellectu.
7 Reply to Objection 2: Although God knows Himself and all else by His own essence, yet His essence is the operative principle of all things, except of Himself. It has therefore the nature of an idea with respect to other things; though not with respect to Himself.
7 Ad secundum dicendum quod, licet Deus per essentiam suam se et alia cognoscat, tamen essentia sua est principium operativum aliorum, non autem sui ipsius, et ideo habet rationem ideae secundum quod ad alia comparatur, non autem secundum quod comparatur ad ipsum Deum.
8 Reply to Objection 3: God is the similitude of all things according to His essence; therefore an idea in God is identical with His essence.
8 Ad tertium dicendum quod Deus secundum essentiam suam est similitudo omnium rerum. Unde idea in Deo nihil est aliud quam Dei essentia.