After spending the prime of life in these pursuits at Rome, he returned to his native duchy, where his instructions in mathematics were sought by Prince Francesco Maria, with whom he read and expounded Euclid's _Elements_; and afterwards, at the request of his pupil, published a Latin translation of them. It was about 1569 that he was visited there by a young Englishman named John Dea, whose love of the exact sciences induced him to seek so distinguished a professor, and who supplied him with some Arabic MSS., hitherto unknown.[136] Six years thereafter he was surprised by death, with many unfinished works on his hands, part whereof saw the light under the superintendence of the Marquis Guidobaldo del Monte. The life of a hard student is rarely one of varied incident; and even the voluble pen of his pupil Baldi has failed to illustrate that of Comandino with interest, beyond his scholiast labours.[137] Yet severity formed no part of his social character, and he was ready at all times to relax his toils by Epicurean indulgences, which are said eventually to have curtailed his life. To the last, however, his engrossing pleasure was in books; and, although his works number more translations than original compositions, he is ranked by Montucla among the most able and judicious of commentators. [Footnote 136: GROSSI, _Uomini Illustri di Urbino_.] [Footnote 137: It is printed in the Raccolta Calogeriana, XIX., 140.] * * * * * One of the pupils whom Comandino left in his native state was GUIDOBALDO, MARQUIS DEL MONTE, who was born of distinguished lineage, in 1544. Tiraboschi has cited, as a singular proof of the engrossing nature of his studies, the fact that his life offers a nearly total want of incident. So tranquilly did his days flow on at his castle of Monte Baroccio, amid abstruse occupations, that he seemed to have forgotten a world unconscious of his very existence, and the only memorials of his life are his works. His treatise upon Perspective successfully carried forward what had been indicated by Pietro della Francesca in the preceding century, and he was afterwards engaged upon the doctrine of Planispheres, the correction of the kalendar, and the solution of astronomical problems. But though thus devoted to abstruse science, he spared a portion of his thoughts for its practical branches, working upon mechanics, and translating from Archimedes. It is unnecessary here to go into an examination of results which modern discoveries have left far behind; the ground has been well sifted by Montucla, whose work indicates whatever is still of value in this class of now somewhat superseded labours. The Marquis was addressed by Torquato Tasso in a sonnet beginning _Miserator de' gran celesti campi_, and died early in the seventeenth century, survived by a younger brother, Francesco Maria, who had been made cardinal by Sixtus V. * * * * *