"Shylock observes, that there are land thieves and water thieves; and as De Foe was familiar with the latter, so he was not without some knowledge of the practices and devices of the former. We are afraid we must impute to his long imprisonment the opportunity of becoming acquainted with the secrets of thieves and mendicants, their acts of plunder, concealment, and escape. But whatever way he acquired his knowledge of low life, De Foe certainly possessed it in the most extensive sense, and applied it in the composition of several works of fiction in the style termed by the Spaniards _Gusto Picaresco_, of which no man was ever a greater master. This class of fictitious narration may be termed the Romance of Roguery, the subjects being the adventures of thieves, rogues, vagabonds, swindlers, viragoes, and courtezans. The strange and blackguard scenes which De Foe describes, are fit to be compared to the Gipsy Boys of Murillo, which are so justly admired as being, in truth of conception and spirit of execution, the very _chef-d'[oe]uvre_ of art, however low and loathsome the originals from which they were taken. "A third species of composition, to which the author's active and vigorous genius was peculiarly adapted, was the account of great national convulsions, whether by war, or by the pestilence, or the tempest. These are tales which are sure when even moderately well told, to arrest the attention, and which, narrated with that impression of reality which De Foe knew so well how to convey, make the hair bristle and the skin creep. In this manner he has written the Memoirs of a Cavalier, which have been often read and quoted as the real production of a real personage. Born himself almost immediately after the Restoration, De Foe must have known many of those who had been engaged in the civil turmoils of 1642-6, to which the period of these memoirs refers. He must have lived among them at the age when boys, such as we conceive De Foe must necessarily have been, cling to the knees of those who can tell them of the darings, the dangers of their youth, at a period when their own passions and views of pressing forward in life have not begun to operate upon their minds, and while they are still pleased to listen to the adventures which others have encountered on that stage which they themselves have not yet entered upon. The Memoirs of a Cavalier have certainly been enriched by some such anecdotes as were likely to fire De Foe's active and powerful imagination, and hint to him in what colours the subject ought to be treated. The contrast, for instance, between the soldiers of the celebrated Tilly and those of the illustrious Gustavus Adolphus, almost seems too minutely drawn to have been executed from anything short of oracular testimony. But De Foe's genius has shown, in this and other instances, how completely he could assume the character he describes.