y
strain, expressing regret that his guest should have left Milan without
seeing D'Avalos, and fear lest he might have prejudiced his fortunes by
taking such a step. He then goes on to describe to Tartaglia the progress
he is making in his work with the Practice of Arithmetic, and to ask him
for help in solving one of the cases in Algebra, the rule for which was
indeed contained in Tartaglia's verses, but expressed somewhat obscurely,
for which reason Cardan had missed its meaning.[98] In his reply,
Tartaglia ignores Jerome's courtesies altogether, and tells him that what
he especially desires at the present moment is a sight of that volume on
the Practice of Arithmetic, "for," says he, "if I do not see it soon, I
shall begin to suspect that this work of yours will probably make manifest
some breach of faith; in other words, that it will contain as
interpolations certain of the rules I taught you." Niccolo then goes on to
explain the difficulty which had puzzled Cardan, using terms which showed
plainly that he had as poor an opinion of his correspondent's wit as of
his veracity.

Cardan was an irascible man, and it is a high tribute to his powers of
restraint that he managed to keep his temper under the uncouth insults of
such a letter as the foregoing. The more clearly Tartaglia's jealous,
suspicious nature displays itself, the greater seems the wonder that a man
of such a disposition should ever have disclosed such a secret. He did not
believe Cardan when he promised that he would not publish the rules in
question without his (the discoverer's) consent--why then did he believe
him when he swore by the Gospel? The age was one in which the binding
force of an oath was not regarded as an obligation of any particular
sanctity if circumstances should arise which made the violation of the
oath more convenient than its observance. However, the time was not yet
come for Jerome to begin to quibble with his conscience. On May 12, 1539,
he wrote another letter to Tartaglia, also in a very friendly tone,
reproaching him gently for his suspicions, and sending a copy of the
_Practice of Arithmetic_ to show him that they were groundless. He
protested that Tartaglia might search from beginning to end without
finding any trace of his jealously-guarded rules, inasmuch as, beyond
correcting a few errors, the writer had only carried Algebra to the point
where Fra Luca had left it. Tartaglia searched, and though he could not
put his finge