Summa Theologica

Having treated the Creation, Aquinas now considers how God rules the universe and human affairs. 

Aquinas affirms that all things in the universe are subject to God’s rule and providence, not chance. We see that in nature things nearly always work out for the best, as if they are directed to a certain end. There is an obvious order in nature that points to God. God not only brings things into being, but also brings them to perfection and leads them to their end, which is himself. The effect of God’s government on human beings is to make them more like him, in being good and in becoming the cause of goodness in others. Although some things in the world have an element of chance to them, they are under the ultimate control of God’s rule. 

Exploring God’s rule in more depth, the following questions deal with various things that God does to, or in, created things.

God, in addition to creating all things, maintains them in being. Otherwise, they would lapse into nothingness. While it is possible for God to annihilate created beings, he does not and will not do this.