Towards the end of 1259 Thomas left Paris and returned, as a Master, to Italy, probably to Naples where he revised in part what he had already written in Paris. He finished writing out the Summa contra gentiles of which we have some parts of an autograph. This work came to be other than was originally intended, that is a theological manual for missionaries around the world. It became instead a very general list of philosophical and theological objections. Divided into four books, the Summa occupies itself with progressively: The existence of God according to Reason (Book I); the emanation of creatures from God (Book II); the providence of God for creatures which he has created and governs (Book III); and, finally, the mysteries of the Christian faith: the Trinity, the Incarnation of God, the Sacraments, and Last Things (Book IV).