Dr. Joseph Hattrup received his M.A. and Ph.D. in Philosophy from the Center for Thomistic Studies at the University of St. Thomas in Houston. He wrote his dissertation on Aristotle’s teaching concerning substance in the Categories and the Metaphysics. He currently teaches at Thomas Aquinas College, in Santa Paula, California. His chief interests remain Aristotelian logic and metaphysics, but he has written on various topics, including the liberal arts of astronomy and music, and Virgil’s influence on Western literature and poetry.