That it belongs to God to be to other Beings the Principle of Existence

In inferior agents it is a sign of attained perfection, when they can produce their own likeness. But God is sovereignly perfect (B.I. Chap. XXVIII). Therefore it belongs to Him to make some being like Himself in actual existence.

6. The more perfect any principle of activity is, the wider its sphere of action. But that pure actuality, which is God, is more perfect than actuality mingled with potentiality, such as is in us. Now actuality is the principle of action. Since then by the actuality which is in us, we are not only capable of immanent acts, such as understanding and willing, but also of acts tending to exterior things and productive of effects, much more can God, by virtue of His actuality, not only understand and will, but also produce an effect.Who maketh great and wonderful and inscrutable works without number (Job v.9).

2.5 : Order of matters to be treated
2.7 : That there is in God Active Power