1 6 JEROME CARDAN 



own subject. He deemed it the more salutary discipline 

 proofs of which opinion he would often bring forward 

 out of Aristotle that it was better adapted for the 

 acquisition of power and riches ; and that it would help 

 me more efficiently in restoring the fortunes of our 

 house. He perceived moreover that the office of teach- 

 ing in the schools of the city, together with its accom- 

 panying salary of a hundred crowns which he had 

 enjoyed for so many years, would not be handed on to 

 me, as he had hoped, and he saw that a stranger would 

 succeed to the same. Nor was that commentary of his 

 destined ever to see the light or to be illustrated by my 

 notes. Earlier in life he had nourished a hope that his 

 name might become illustrious as the emendator of the 

 ' Commentaries of John, Archbishop of Canterbury on 

 Optics and Perspective.' 1 Indeed the following verses 

 were printed thereanent : 



' Hoc Cardana viro gaudet domus : omnia novit 

 Unus : habent nullum saecula nostra parem.' 



" These words may be taken as a sort of augury re- 

 ferring rather to certain other men about to set forth to do 

 their work in the world, than to my father, who, except 

 in the department of jurisprudence (of which indeed 



1 John Peckham was a Franciscan friar, and was nominated to 

 the see of Canterbury by Nicholas III. in 1279. He had spent 

 much time in the convent of his Order at Oxford, and there is a 

 legend connecting him with a Johannes Juvenisor John of London, 

 a youth who had attracted the attention and benevolence of Roger 

 Bacon. This Johannes became one of the first mathematicians 

 and opticians of the age, and was sent to Rome by Bacon, who 

 entrusted to him the works which he was sending to Pope Clement 

 IV. There is no reason for this view beyond the fact that both 

 were called John, and distinguished in the same branches of learn- 

 ing. The Perspectiva Communis was his principal work ; it does 

 not deal with perspective as now understood, but with elementary 

 propositions of optics. It was first printed in Milan in or about 1482. 



