He composed sermons.

A missionary once ordered half-a-dozen of them for consumption in the Portuguese colonies, and paid him fifty crowns apiece, which Diderot counted far from the worst bargain of his life.

All this was beggarly toil for a man of genius, but Diderot never took the trouble to think of himself as a man of genius, and was quite content with life as it came.

If he found himself absolutely without food and without pence, he began moodily to think of abandoning his books and his pen, and of complying with the wishes of his father.

A line of Homer, an idea from the Principia, an interesting problem in algebra or geometry, was enough to restore the eternally invincible spell of knowledge.