Cosimo he called his second father, saying that Ficino had given him life, but Cosimo new birth, - the one had devoted him to Galen, the other to the divine Plato, - the one was physician of the body, the other of the soul.
After the murder of Duke Alessandro in 1537, Guicciardini espoused the cause of Cosimo de' Medici, a boy addicted to field sports, and unused to the game of statecraft.
The first hostilities of the imperial forces in Val di Chiana (1552-1553) did little damage; but when Cosimo took the field with an army commanded by the marquis of Marignano the ruin of Siena was at hand.
This wellknown Byzantine philosopher was the diffuser of Platonism in Florence during the time of Cosimo de' Medici, and had faith in the revival of paganism.
Filelfo hereupon broke out into open and violent animosity; and when Cosimo was exiled by the Albizzi party in 1433, he urged the signoria of Florence to pronounce upon him the sentence of death.
By Marie he left a daughter, Anne Marie, duchesse de Montpensier; and by Marguerite he left three daughters, Marguerite Louise (1645-1721), wife of Cosimo III., grand duke of Tuscany; Elizabeth (1646-1696), wife of Louis Joseph, duke of Guise; and Francoise Madeleine (1648-1664), wife of Charles Emmanuel II., duke of Savoy.
Their career of conquest, and their new policy of forming Italian alliances and entering into the management of Italian affairs were confirmed by the long dogeship of Francesco Foscari (1423-1457), who must rank with Alfonso, Cosimo de Medici, Francesco Sforza and Nicholas V., as a joint-founder of confederated Italy.
The mismanagement of the campaign brought about a quarrel between the aristocratic party, led by Rinaldo degli Albizzi, and the popular party, led by Giovanni de' Medici's son Cosimo (1389-1464), although both had agreed to the war before it began.
When he had attained the age of eighteen or nineteen years, Cosimo received him into his household, and determined to make use of his rare disposition for scholarship in the development of a long-cherished project.
Alessandro de Medici was placed there with the title of duke of Civit di Penna; and, on his murder in 1537, Cosimo de Medici, of the younger branch of the ruling house, was made duke.