to D'Avalos, but now it was offered to him it seemed a burden
rather than a benefit. He disliked the notion of going to Milan; yet, if
he did not go, the Marchese d'Avalos might take offence. But in the end he
decided to undertake the journey; and, as D'Avalos happened then to be
absent from Milan on a visit to his country villa at Vigevano, he stayed
for three days in Cardan's house. As a recorder of conversations Tartaglia
seems to have had something of Boswell's gift. He gives an abstract of an
eventful dialogue with his 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 discourtesy 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--if you will make them known to me--but that I will
promise and pledge my faith of