Thomas Aquinas was a theologian and philosopher. His two most important works areSumma contra gentiles, and Summa Theologica. He contended that a doctrine of creation out of nothing (by a Supreme Creator) is completely harmonious with the discovery of causes in nature. A doctrine of creation out of nothing, by the first cause God (Something), affirms the fundamental dependence of all being upon God as its cause.
Aquinas’ belief was that all of life is a search for happiness and that the "ultimate happiness possible in this life must lie in the consideration of first causes…”Aquinas applies different kinds of causality to God. He upholds that God is the initial, consummate, effective, and final principle of all things. God acts basically as an efficient cause. God is the Primary Cause.
Secondary Causality to Thomas Aquinas was that it is better for God to do through secondary causes what he can and could do by Himself. He believed that a primary cause had a greater influence on its effect than a secondary cause. He showed that this is true of God – or the First Cause – in the causality of being. The First Cause causes things to be or exist. Secondary causes (which are true causes) give their effects or outcomes limited being. Secondary causes do this via the power of the primary cause.