In What Sense Is Nature Incomplete?
“Society is a product of human action, i.e., the human urge to remove uneasiness as far as possible. In order to explain its becoming and its evolution it is not necessary to have recourse to a doctrine, certainly offensive to a truly religious mind, according to which the original creation was so defective that reiterated superhuman intervention is needed to prevent its failure.” (Human Action, 146ff) The universe is complete and self-sufficient in the sense that God does not occupy His eternity protecting the creation from an inevitable collapse. God does not push particles of matter around nor drags things through the vacuum nor keeps the earth from falling into the sun nor brings the economy into equilibrium. Nature knows how to take care of itself. God does no violence to nature, such as when nature wants to do X but God intervenes and forces it to to Y instead, other than through explicit miracles.
But nature is incomplete in two senses. First, there is in it both act and potency. Second, even considering any thing in the universe or the universe as a whole insofar as it is in act, this act is imperfect. If we could demonstrate that there exists something that is (1) pure act and (2) perfect act, we would successfully embark upon discussing God.
Of course, the pure actuality of God will let us reason about God’s first level via remotion; whereas God’s perfection will allow us to understand His second level via positive theology.