(CG 2/19-20) That Creation is not Successive (Book 2: God The Origin of Creatures) (Summa Contra Gentiles) (Aquinas, Thomas, St.)

Since the order of actions is according to the order of agents, and the action is nobler of the nobler agent, the first and highest action must be proper to the first and highest agent. But creation is the first and highest action, presupposing no other, and in all others presupposed. Therefore creation is the proper action of God alone, who is the highest agent.

2. Nothing else is the universal cause of being but God (Chap. XV).

3. Effects answer proportionally to their causes. Thus actual effects we attribute to actual causes, potential effects to potential causes, particular effects to particular causes, and universal effects to universal causes. Now the first thing caused is 'being,' as we see by its presence in all things. Therefore the proper cause of 'being,' simply as such, is the first and universal agent, which is God. Other agents are not causes of 'being,' simply as such, but causes of 'being this,' as 'man' or 'white': but 'being,' simply as such, is caused by creation, which presupposes nothing, because nothing can be outside of the extension of 'being,' simply as such. Other productions result in 'being this,' or 'being of this quality': for out of pre-existent being is made 'being this,' or 'being of this quality.'

6. Every agent that acts as an instrument completes the action of the principal agent by some action proper and connatural to itself, as a saw operates to the making of a stool by cutting. If then there be any nature that operates to creation as an instrument of the prime creator, this being must operate through some action due and proper to its own nature. Now the effect answering to the proper action of an instrument is prior in the way of production to the effect answering to the principal agent; hence it is that the final end answers to the principal agent: for the cutting of the wood is prior to the form of the stool. There must then be some effect due to the proper operation of the instrument used for creation; and this effect must be prior in the way of production to 'being': for 'being' is the effect answering to the action of the prime creator. But that is impossible: for the more general is prior in the way of generation to the more particular.

Hereby is destroyed the error of certain philosophers, who said that God created the first spirit, and by it was created the second, and so in order to the last.