Objection 1. It would seem that God cannot create anything, because, according to the Philosopher (Phys. i, text 34), the ancient philosophers considered it as a commonly received axiom that "nothing is made from nothing." But the power of God does not extend to the contraries of first principles; as, for instance, that God could make the whole to be less than its part, or that affirmation and negation are both true at the same time. Therefore God cannot make anything from nothing, or create.
Objection 2. Further, if to create is to make something from nothing, to be created is to be made. But to be made is to be changed. Therefore creation is change. But every change occurs in some subject, as appears by the definition of movement: for movement is the act of what is in potentiality. Therefore it is impossible for anything to be made out of nothing by God.
Objection 3. Further, what has been made must have at some time been becoming. But it cannot be said that what is created, at the same time, is becoming and has been made, because in permanent things what is becoming, is not, and what has been made, already is: and so it would follow that something would be, and not be, at the same time. Therefore when anything is made, its becoming precedes its having been made. But this is impossible, unless there is a subject in which the becoming is sustained. Therefore it is impossible that anything should be made from nothing.
Objection 4. Further, infinite distance cannot be crossed. But infinite distance exists between being and nothing. Therefore it does not happen that something is made from nothing.
On the contrary, It is said (Genesis 1:1): "In the beginning God created heaven and earth."
I answer that, Not only is it not impossible that anything should be created by God, but it is necessary to say that all things were created by God, as appears from what has been said (44, 1). For when anyone makes one thing from another, this latter thing from which he makes is presupposed to his action, and is not produced by his action; thus the craftsman works from natural things, as wood or brass, which are caused not by the action of art, but by the action of nature. So also nature itself causes natural things as regards their form, but presupposes matter. If therefore God did only act from something presupposed, it would follow that the thing presupposed would not be caused by Him. Now it has been shown above (44, 1,2), that nothing can be, unless it is from God, Who is the universal cause of all being. Hence it is necessary to say that God brings things into being from nothing.
Reply to Objection 1. Ancient philosophers, as is said above (Question 44, Article 2), considered only the emanation of particular effects from particular causes, which necessarily presuppose something in their action; whence came their common opinion that "nothing is made from nothing." But this has no place in the first emanation from the universal principle of things.
Reply to Objection 2. Creation is not change, except according to a mode of understanding. For change means that the same something should be different now from what it was previously. Sometimes, indeed, the same actual thing is different now from what it was before, as in motion according to quantity, quality and place; but sometimes it is the same being only in potentiality, as in substantial change, the subject of which is matter. But in creation, by which the whole substance of a thing is produced, the same thing can be taken as different now and before only according to our way of understanding, so that a thing is understood as first not existing at all, and afterwards as existing. But as action and passion coincide as to the substance of motion, and differ only according to diverse relations (Phys. iii, text 20,21), it must follow that when motion is withdrawn, only diverse relations remain in the Creator and in the creature. But because the mode of signification follows the mode of understanding as was said above (Question 13, Article 1), creation is signified by mode of change; and on this account it is said that to create is to make something from nothing. And yet "to make" and "to be made" are more suitable expressions here than "to change" and "to be changed," because "to make" and "to be made" import a relation of cause to the effect, and of effect to the cause, and imply change only as a consequence.
Reply to Objection 3. In things which are made without movement, to become and to be already made are simultaneous, whether such making is the term of movement, as illumination (for a thing is being illuminated and is illuminated at the same time) or whether it is not the term of movement, as the word is being made in the mind and is made at the same time. In these things what is being made, is; but when we speak of its being made, we mean that it is from another, and was not previously. Hence since creation is without movement, a thing is being created and is already created at the same time.
Reply to Objection 4. This objection proceeds from a false imagination, as if there were an infinite medium between nothing and being; which is plainly false. This false imagination comes from creation being taken to signify a change existing between two forms.
Source: Summa Theologica (New Advent)