The germ which in his fertile mind grew into _Robinson Crusoe_ fell from the real adventures of Alexander Selkirk, whose solitary residence of four years on the island of Juan Fernandez was a nine days' wonder in the reign of Queen Anne.
Defoe was too busy with his politics at the moment to turn it to account; it was recalled to him later on, in the year 1719, when the exploits of famous pirates had given a vivid interest to the chances of adventurers in far-away islands on the American and African coasts.

The _Life, Adventures, and Piracies of the famous Captain Singleton_, who was set on shore in Madagascar, traversed the continent of Africa from east to west past the sources of the Nile, and went roving again in the company of the famous Captain Avery, was produced to satisfy the same demand.

Such biographies as those of _Moll Flanders_ and the _Lady Roxana_ were of a kind, as he himself illustrated by an amusing anecdote, that interested all times and all professions and degrees; but we have seen to what accident he owed their suggestion and probably part of their materials.

He had tested the market for such wares in his Journals of Society.
In following Defoe's career, we are constantly reminded that he was a man of business, and practised the profession of letters with a shrewd eye to the main chance.

He scoffed at the idea of practising it with any other object, though he had aspirations after immortal fame as much as any of his more decorous contemporaries.