Plato. Contra Celsum is widely regarded by modern scholars as one of the most important works of early Christian apologetics. Other apologists from this period are Aristides of Athens, the author of the Epistle to Diognetus, Aristo of Pella, Tatian, Justin Martyr, Melito of Sardis, Athenagoras of Athens, Theophilus of Antioch, Irenaeus, Origen, Hippolytus of Rome, Tertullian, Minucius Felix, Cyprian, and Victorinus of Pettau, Middle Ages and Early Modern Period Anselm of Canterbury propounded the ontological argument in his Proslogion. Thomas Aquinas presented five ways, or arguments for God's existence, in the Summa Theologica, while his Summa contra Gentiles was a major apologetic work. Aquinas also made significant criticisms of the ontological argument which resulted in its losing popularity until it was revived by Rene Descartes in his Meditations. Blaise Pascal outlined an approach to apologetics in his Pensées: "Men despise religion; they hate it and fear it is true. To remedy this, we must begin by showing that religion is not contrary to reason; that it is venerable, to inspire respect for it; then we must make it lovable, to make good men hope it is true; finally, we must prove it is true." Late Modern Period Christian apologetics continues in modern times in a wide variety of forms. Among the Roman Catholics there are Bishop Robert Barron, G. K. Chesterton, Ronald Knox, Taylor Marshall, Arnold Lunn, Karl Keating, Michael Voris, Peter Kreeft, Frank Sheed, Dr. Scott Hahn, and Patrick Madrid. The Russian Orthodox Seraphim Rose is perhaps the best known modern, English speaking Eastern Orthodox apologist. Among the Evangelicals there is the Anglican C. S. Lewis (who popularized the argument now known as Lewis's trilemma). Among Protestant apologists of the 19th century there was William Paley who popularized the Watchmaker analogy. In the first half of the 20th century, many Christian fundamentalists became well known apologists. Some of the best known are R. A. Torrey and John Gresham Machen. Evangelical Norman Geisler, Lutheran John Warwick Montgomery and Presbyterian Francis Schaeffer were among the most prolific Christian apologists in the latter half of the 20th century and into the 21st, while Gordon Clark and Cornelius Van Til started a new school of philosophical apologetics called presuppositionalism, which is popular in Calvinist circles. Others include William Lane Craig, Douglas Groothuis, Josh McDowell, Hugo Anthony Meynell, Timothy J. Keller, Francis Collins, Vishal Mangalwadi, Richard Bauckham, Craig Evans, Darrell Bock, John F.