The following letters from Louis XI., from Lorenzo, and from Sixtus IV., relate to the famous Pazzi conspiracy when Giuliano de’ Medici was murdered and Lorenzo wounded in the cathedral of Florence. Antagonism and rivalry had for some time existed between the two great families, although Lorenzo’s favourite sister Bianca was married to Gugliemo de’ Pazzi, who had been regarded by Piero almost as his own son, and is often mentioned in these letters as the companion of the Magnificent on hunting excursions and visits to foreign courts. Gugliemo’s brother Francesco, head of the Pazzi bank at Rome, worked incessantly against Lorenzo’s uncle Giovanni Tornabuoni, manager of the Roman branch of the Medici bank, and eventually succeeded in depriving him of the business of the Holy See given to Lorenzo in the first days of Sixtus’ rule. The third brother, Giovanni de’ Pazzi, was married to Beatrice Borromeo, who on the death of her father without having made a will claimed, according to the existing laws, the whole of his property. His nephews, however, intimate friends of the two young Medici, contested her right, and in 1476 a retrospective law of intestacy was passed setting aside the claims of females to the estate of a father who died intestate, and giving it to the nearest male relative. Machiavelli, Nardi, and Guicciardini, all accuse Lorenzo of instigating the drafting of “this law made for the occasion,” as Nardi calls it. Roscoe maintains that it was passed more than ten years before, but the proofs he adduces are quite illusory. Without extraneous aid it is however very improbable that the Pazzi would have dared to attempt the assassination of the two brothers Medici. This aid they obtained from the Pope. Sixtus IV. had, as Dr. Creighton says, “elevated nepotism into political principle ... he took his nephews, men of no position and little capacity, and placed at their disposal all the resources of the Roman See.” Giuliano della Rovere and Piero Riario were created cardinals in total disregard of the regulations of the Conclave, while for Piero’s brother, Girolamo, he bought Imola from the Duke of Milan, at the same time arranging a marriage between him and Caterina Sforza, the Duke’s illegitimate daughter. Florence had long coveted Imola, and Lorenzo tried to prevent the purchase by raising difficulties about advancing the necessary money to the Pope. Francesco de’ Pazzi then seized his opportunity and was appointed Treasurer to the Holy See in Lorenzo’s place.