One of the great works of Thomas Aquinas, probably written around 1264. Its purpose is in debate, but it was probably written as a manual of philosophy and theology for missionaries to the Moors. It provides much supporting material for the more famous Summa Theologicae. Its correct title is Liber de veritate catholicae fidei contra errores infidelium ("The Book on the Truth of the Catholic faith against the Errors of the Infidels")