The youth of Leonardo thus passed away in the pursuit of science and of art; sometimes he was deeply engaged in astronomical calculations and investigations; sometimes ardent in the study of natural history, botany, and anatomy; sometimes intent on new effects of color, light, shadow, or expression in representing objects animate or inanimate. Versatile, yet persevering, he varied his pursuits, but he never abandoned any. He was quite a young man when he conceived and demonstrated the practicability of two magnificent projects: one was to lift the whole of the church of San Giovanni, by means of immense levers, some feet higher than it now stands, and thus supply the deficient elevation; the other project was to form the Arno into a navigable canal as far as Pisa, which would have added greatly to the commercial advantages of Florence. It happened about this time that a peasant on the estate of Piero da Vinci brought him a circular piece of wood, cut horizontally from the trunk of a very large old fig-tree, which had been lately felled, and begged to have something painted on it as an ornament for his cottage. The man being an especial favorite, Piero desired his son Leonardo to gratify his request; and Leonardo, inspired by that wildness of fancy which was one of his characteristics, took the panel into his own room, and resolved to astonish his father by a most unlooked-for proof of his art. He determined to compose something which should have an effect similar to that of the Medusa on the shield of Perseus, and almost petrify beholders. Aided by his recent studies in natural history, he collected together from the neighboring swamps and the river-mud all kinds of hideous reptiles, as adders, lizards, toads, serpents: insects, as moths, locusts, and other crawling and flying obscene and obnoxious things; and out of these he composed a sort of monster or chimera, which he represented as about to issue from the shield, with eyes flashing fire, and of an aspect so fearful and abominable that it seemed to infect the very air around. When finished, he led his father into the room in which it was placed, and the terror and horror of Piero proved the success of his attempt. This production, afterward known as the "Rotello del Fico," from the material on which it was painted, was sold by Piero secretly for one hundred ducats to a merchant, who carried it to Milan, and sold it to the duke for three hundred. To the poor peasant, thus cheated of his "Rotello," Piero gave a wooden shield, on which was painted a heart transfixed by a dart, a device better suited to his taste and comprehension. In the subsequent troubles of Milan, Leonardo's picture disappeared, and was probably destroyed as an object of horror by those who did not understand its value as a work of art.