God is the sovereign master of his plan. But to carry it out he also makes use of his creatures’ co-operation. This use is not a sign of weakness, but rather a token of almighty God’s greatness and goodness. For God grants his creatures not only their existence, but also the dignity of acting on their own, of being causes and principles for each other, and thus of co-operating in the accomplishment of his plan.
To human beings God even gives the power of freely sharing in his providence by entrusting them with the responsibility of “subduing” the earth and having dominion over it. God thus enables men to be intelligent and free causes in order to complete the work of creation, to perfect its harmony for their own good and that of their neighbors. Though often unconscious collaborators with God’s will, they can also enter deliberately into the divine plan by their actions, their prayers and their sufferings. They then fully become “God’s fellow workers” and co-workers for his kingdom.
The truth that God is at work in all the actions of his creatures is inseparable from faith in God the Creator. God is the first cause who operates in and through secondary causes: “For God is at work in you, both to will and to work for his good pleasure.” Far from diminishing the creature’s dignity, this truth enhances it. Drawn from nothingness by God’s power, wisdom and goodness, it can do nothing if it is cut off from its origin, for “without a Creator the creature vanishes.” Still less can a creature attain its ultimate end without the help of God’s grace.
From the Catechism of the Catholic Church 306-308