the Summa contra Gentiles, the first of his two masterpieces. The claim was made in the sixteenth century that Thomas wrote this work as a ‘missionary handbook’ for Catholic representatives in the world of Islam, but attention to its contents suggests a wider aim, negatively convicting of error those who brought arguments against the faith from a great diversity of standpoints, from out-and-out pagans to Christian heretics and, more positively, showing the beautiful intelligibility of the suprarational