There is no part of the present book which will not delight and instruct the general reader; but the most original portions are those devoted to practical remarks on mental diseases and to acute observations on minor topics of the great subject. To all who know Sidney Smith’s writings it is needless to add, that every idea in the volume is conceived and stated clearly, and that the author’s ignorance in the higher regions of his theme never seeks refuge in obscure terms, but is boldly, and some times exultingly, acknowledged. Many of the great philosophers, and especially the idealists and skeptics, are rather fleeringly disposed of. Common sense is Sydney’s test; but common sense is hardly able to grapple with Aristotle and Descartes, the greatest of metaphysicians; and they are, therefore, praised for their power and ridiculed for its perversion. The author’s peculiar felicity in making ludicrous statements which operate with the force of arguments, is displayed throughout the volume. “Bishop Berkeley,” he says, “destroyed this world in one volume octavo, and nothing remained after his time but mind; which experienced a similar fate from the hand of Mr. Hume, in 1737.” Nothing could be more felicitous than this statement, considered as a practical argument against the systems of the idealists and skeptics. Again he says: “A great philosopher may sit in his study, and deny the existence of matter; but if he take a walk into the streets he must take care to leave his theory behind him. Pyrrho said there was no such thing as pain; and he saw no _proof_ that there were such things as carts and wagons; and he refused to get out of their way: but Pyrrho had, fortunately for him, three or four stout slaves, who followed their master without following his doctrine; and whenever they saw one of these ideal machines approaching, took him up by the arms and legs, and, without attempting to controvert his arguments, put him down in a place of safety.”