Beltrando Costabili, the Ferrarese orator, concluded a letter dated August 14th with the remark: “It is not strange that the Pope and Caesar are sick, because almost all the prominent men in Rome are ill--and especially in the Vatican, owing to the bad air.” Stories of the poisoning began to circulate as soon as the rapidity with which the body putrefied became known.
Guicciardini’s account has been followed by all later writers until the present day, and he was one of the bitterest of the enemies of the Borgia. According to his statement, before Caesar’s departure for the field he and the Pope were invited to dine with Cardinal Adriano di Corneto. Romolino, Valentino’s intimate, and two other cardinals were also present. One of the Borgia, desiring to secure possession of their host’s property, decided to poison him, but the servants confused the glasses and gave Alexander and Caesar the envenomed cups. This account was based on a letter written by Peter Martyr of Anghiara, from Segovia, November 10, 1503--that is, about three months after the death of the Pope. None of the ambassadors in Rome, who were closely following events in the Vatican, even hinted at poison at the time.
The facts, briefly summarised, were as follows: The dinner took place August 5th; Caesar and the Pope fell ill the 10th; the latter was feverish the 12th; the 16th he was bled copiously and his illness became serious; the 17th he was given an exceedingly powerful draught of some sort which failed to relieve him; the 18th, feeling that his end was approaching, he confessed to the Bishop of Carniola, who administered the Communion. Later, Mass was celebrated at his bedside in the presence of five cardinals. The Pope was extremely weak and he declared that he felt death was near. The Bishop of Carniola administered the Extreme Unction and a few hours later the Holy Father expired--thirteen days after the dinner in Cardinal Corneto’s garden, which precludes the idea of poison.
Giustinian makes no mention of poison. Beltrando Costabili, the Ferrarese ambassador, who followed the course of the Pope’s illness from hour to hour, likewise does not suggest it. Alexander VI. was probably merely one of the many victims reaped by the plague in Rome in 1503.