Intellectual life is not a thing apart from the humanizing and moralizing influences that moral virtues provide. Saint Thomas’s teachings about moral virtues suggest how essential he considers them for a flourishing speculative life. He makes all this very clear in the Second Part of the Summa Theologiae. The potential parts of fortitude which have a crucial role in intellectual work are patience, perseverance and magnanimity. In this article I show how these potential virtues act in speculative life.