Medieval Christians dubbed Thomas Aquinas (1225-1274) the Angelic Doctor. No wonder they did. His penetrating thoughts probed the depths of divine revelation.

Few thinkers have shaped Christians' minds and stirred their hearts more profoundly. Begun in 1265 but unfinished at his death, the Summa Theologica is Thomas's magnum opus. In it he sets forth cases for the existence and nature of God. He teaches and defends the Christian faith's solid foundation.

Some Christian thinkers influence the day in which they live. Some, like Thomas, leave a profound impact on generations. Some pastors and theologians speak only to the head, and some, only to the heart. A precious few can speak with carefulness and charity to both, and Thomas Aquinas may be chief among them.