This lecture was given on December 7, 2021 at the University of Wisconsin, Madison. The handout for this lecture can be found here: https://tinyurl.com/mrrhu2sp. For more information on upcoming events, please visit our website at www.thomisticinstitute.org. About the speaker: Gregory T. Doolan received his B.A. in political theory from Georgetown University in 1993 and his Ph.D. in philosophy from The Catholic University of America in 2003. He taught philosophy at the Dominican House of Studies in Washington, D.C. from 2004–05 and joined the faculty of the School of Philosophy at the Catholic University of America in 2005. Dr. Doolan’s research interest is in the area of Aquinas’s metaphysics; in recent years, his focus has been on Aquinas’s account of the Aristotelian categories of being. A native of Philadelphia, Dr. Doolan currently lives in Washington, D.C. with his wife and three children.