"Although, in relation to the foreknowledge, and decree of God, the first cause, all things come to pass immutably and infallibly, yet, by the same providence, he ordereth them to fall out according to the nature of second causes, either necessarily, freely, or contingently."
Westminster Confession of Faith, Chapter 5 (1647)
"The doctrine of providence has to do with God's governance of the universe. God does more than observe the universe. He must not be relegated in our thinking to the level of a mere cosmic spectator who creates a world and then sits back to observe what will happen. Such a deity would resemble Aristotle's unmoved mover more than Israel's Yahweh.
"At the same time, the biblical God is not a do-everything king who refuses to delegate. He is a ruler who governs through means, via intermediate agents and forces.
"In the 17th century Rene Descartes made an important distinction between primary and secondary causality. This distinction found its way into the Reformation creeds (most notably the Westminster Confession). Primary causality refers to God's act of creation as well as his ongoing work of sustenance over creation. His sovereighty stands over and above the created order at every moment. This makes him not only the Creator but the Lord of history as well.
"Secondary causality [or second causes] refer to what we commonly call the laws of nature. These "laws" reflect not an independent power of nature but rather the ordinary manner by which God rules his creation. Nature's laws are God's laws. To discover them is to think God's laws after him [a phrase commonly used by Reformation scientists]...."
-- R. C. Sproul, "Providence, Science, and the Sovereignty of God", in Perspectives on Science and Christian Faith, 41(2), June 1989.