Who could doubt that Vauban had been an earthworm, a mole and a rabbit? that Euclid acquired the practical knowledge of geometry when he was a spider; and that the first builder of a pyramid imitated unconsciously the proportionately far greater edifices which he had been employed in raising when he was one of a nation of white ants? Mrs. Dove had been a cowslip, a humble bee, and, lastly, a cushat. He himself had been a Dove and a Serpent—for “Dan was a Serpent by the way;” and moreover he flattered himself that he had the wisdom of the one, and the simplicity of the other. Of his other stages he was not so certain,—except that he had probably once been an inhabitant of the waters, in the shape of some queer fish. CHAPTER CXXVIII. ELUCIDATIONS OF THE COLUMBIAN THEORY. Thou almost makest me waver in my faith To hold opinion with Pythagoras, That souls of animals infuse themselves Into the trunks of men. MERCHANT OF VENICE. Many facts in illustration or exemplification of the Doctor's theory concerning progressive existence must have occurred to every one within the circle of his own observations. One of the scientific persons who abridged the Philosophical Transactions says, he “was acquainted with a medical practitioner of considerable eminence who could not refrain from eating toasted cheese, though he was subject to an alarming pulmonary complaint which was uniformly aggravated by it, and which terminated fatally at an age by no means advanced.” This practitioner, the Doctor would have said, had been either a mouse or a rat, and in that pre-existent form had nibbled at such a bait,—perhaps once too often. This would account for the propensity even if he were not a Welshman to boot. The same author says “there is now living a physician of my acquaintance who at an autumnal dessert, never ceases eating all the filberts he can lay his hands upon, although he very candidly acknowledges that they are extremely indigestible and hurtful things.” Upon the Doctor's theory, who can doubt that he had been a squirrel?