;)

"...For, at whatever instant a thing exists, at that instant it can begin to act, as is clear in the case of all things that come to be by generation: in the very instant at which there is fire, the fire heats. But in an instantaneous action, the beginning & the end of the action are simultaneous, indeed identical, as is clear in the case of all indivisible things. Hence, at whatever moment an agent instantaneously producing an effect exists, the end of its action can exist as well. The end of the action, however, is simultaneous with the thing made. Therefore, there is no contradiction if we suppose that a cause instantaneously producing an effect does not precede its effect in time. A contradiction does obtain if the cause involved is one that produces its effects through motion, for the beginning of the motion precedes in time the end of the motion. Since people are accustomed to considering the type of cause that produces effects through motion, they do not easily grasp that an agent cause may fail to precede its effect in time, & so, having limited experience, they easily make a false generalization.

Nor can the conclusion be avoided by saying that God is an agent cause that acts voluntarily, for neither the will nor the voluntary agent need precede its effect in time, unless the agent cause acts from deliberation, which we take to be absent in God.

Further, a cause that produces the whole substance of a thing does not, in producing a whole substance, act in a less perfect way than does a cause that produces just a form in producing the form. On the contrary, it acts in a much more perfect way, since it does not act by educing from the potentiality of matter, as do causes that merely produce forms. However, some causes that produce just forms are such that, whenever the cause exists, the form produced by it exists as well, as is clear in the case of illumination by the sun. Therefore, much more can God, who produces the whole substance of things, make something caused by him exist whenever he himself exists.

Further, if, granted a cause, its effect does not immediately exist as well, this can only be because something complementary to that cause is lacking: the complete cause & the thing caused are simultaneous. God, however, never lacks any kind of complementary cause in order to produce an effect. Therefore, at any instant at which God exists, so too can his effects, & thus God need not precede his effects in time.

Further, the will of the voluntary agent in no way diminishes his power, & this is especially true with God. But all those who try to answer the arguments of Aristotle (who held that something caused by God had always existed, since like always makes like) say that the conclusion would follow if God were not a voluntary agent. Therefore, allowing that God is a voluntary agent, it still follows that he can make something that he has made never fail to exist. Thus, although God cannot make contradictories true, we have shown that there is no contradiction in saying that an agent cause does not precede its effect in time..."

full text : DE AETERNITATE MUNDI by Thomas Aquinas