God and the Eternal Law

According to St. Thomas Aquinas, “A law is nothing else but a dictate of practical reason emanating from the ruler who governs a perfect community” (P. 1, Q. 91). Since God is eternal, his rule over the universe and his dictates for how it ought to be are eternal as well. The eternal law is not something God made but is identical with God’s unchanging reason and desires for creation.