86 JEROME CARDAN 



host on March 25, 1539, which Cardan begins by a 

 gentle reproach anent his guest's reticence in the matter 

 of the rule of the cosa and the cubus equal to the numerus. 

 Tartaglia's reply to this complaint seems reasonable 

 enough (it must be borne in mind that he is his own 

 reporter), and certainly helps to absolve him from the 

 charge sometimes made against him that he was nothing 

 more than a selfish curmudgeon who had resolved to 

 let his knowledge die with him, rather than share it 

 with other mathematicians of whom he was jealous. 

 He told Cardan plainly that he kept his rules a secret 

 because, for the present, it suited his purpose to do so. 

 At this time he had not the leisure to elaborate farther 

 the several rules in question, being engaged over a 

 translation of Euclid into Italian ; but, when this work 

 should be completed, he proposed to publish a treatise 

 on Algebra in which he would disclose to the world all 

 the rules he already knew, as well as many others which 

 he hoped to discover in the course of his present work. 

 He concludes : " This is the cause of my seeming dis- 

 courtesy towards your excellency. I have been all the 

 ruder, perhaps, because you write to me that you are 

 preparing a book similar to mine, and that you propose 

 to publish my inventions, and to give me credit for the 

 same. This I confess is not to my taste, forasmuch as 

 I wish to set forth my discoveries in my own works, 

 and not in those of others." In his reply to this, Cardan 

 points out that he had promised, if Tartaglia so desired, 

 that he would not publish the rules at all ; but here 

 Messer Niccolo's patience and good manners gave way, 

 and he told Messer Hieronimo bluntly that he did not 

 believe him. Then said Cardan : " I swear to you by 

 the Sacred Evangel, and by myself as a gentleman, that 

 I will not only abstain from publishing your discoveries 



