Cosimo II de' Medici

Succeeded his father Ferdinand I (1549-1609) as Grand Duke of Tuscany in 1609. In the first years of his reign, he was under the influence of his mother, Christina of Lorraine (1565-1636). His chief foreign-policy concern was to preserve peace through the arduous equilibrium between the two major European powers: France and Spain. He strengthened the navy and the merchant marine, and developed Leghorn harbor by having a pier built there.

In  his youth, his preceptor in mathematics was Galileo Galilei (1564-1642), whom he recalled to Tuscany from Padua in 1610, after the astronomical discoveries of the Pisan scientist, appointing him at the same time "First Mathematician and Philosopher to the Grand Duke". Galileo paid homage to the ruling family by naming the four satellites of Jupiter that he had discovered "Medicean stars", and by dedicating his Sidereus Nuncius [Starry Messenger] (Venice, 1610) to the Grand Duke.