They are of use also in throwing light upon the prodigious versatility which could dash off a masterpiece in fiction, and, before the printer's ink was dry, be already at work making it a subordinate instrument in a much wider and more wonderful scheme of activity, his own restless life.
It is curious to find among the _Serious Reflections_ a passage which may be taken as an apology for the practices into which Defoe, gradually, we may reasonably believe, allowed himself to fall.

The substance of the apology has been crystallized into an aphorism by the author of Becky Sharp, but it has been, no doubt, the consoling philosophy of dishonest persons not altogether devoid of conscience in all ages.
"Necessity makes an honest man a knave; and if the world was to be the judge, according to the common received notion, there would not be an honest poor man alive." "A rich man is an honest man, no thanks to him, for he would be a double knave to cheat mankind when he had no need of it.

He has no occasion to prey upon his integrity, nor so much as to touch upon the borders of dishonesty.
Tell me of a man that is a very honest man; for he pays everybody punctually, runs into nobody's debt, does no man any wrong; very well, what circumstances is he in?
Why, he has a good estate, a fine yearly income, and no business to do.

The Devil must have full possession of this man, if he should be a knave; for no man commits evil for the sake of it; even the Devil himself has some farther design in sinning, than barely the wicked part of it.

No man is so hardened in crimes as to commit them for the mere pleasure of the fact; there is always some vice gratified; ambition, pride, or avarice makes rich men knaves, and necessity the poor." This is Defoe's excuse for his backslidings put into the mouth of _Robinson Crusoe_.