Galileo Galilei was born on February 15, 1564, in Pisa, Italy. Galileo was the first of seven children of Vincenzio Galilei, a trader and Giula Ammannati, an upper-class woman who married below her class. When Galileo was a young boy, his father moved the family moved to Florence. Galileo moved into a nearby monastery with the intentions of becoming a monk, but he left the monastery when he was 15 because his father disapproved of his son becoming a monk. .
In November of 1581, Vincenzio Galilei had Galileo enrolled in the University of Pisa School of Medicine because he wanted his son to become a doctor to carry on the family fortune. Vincenzio thought that Galileo should be able to provide for the family when he died, and his sister would need a dowry soon. Galileo had other plans, and in early 1583 he began spending his time with the mathematics professors instead of the medical ones. When his father learned of this, he was furious and traveled 60 miles from Florence to Pisa just to confront his son with the knowledge that he had been "neglecting his studies." The grand duke's mathematician intervened and persuaded Vincenzio to allow Galileo to study mathematics on the condition that after one year, all of Galileo's support would be cut off and he was on his own.
In the spring of 1585, Galileo skipped his final exams and left the university without a degree. He began finding work as a math tutor. In November of 1589, Galileo found a position as a professor of mathematics at the university of Pisa, the same one he had left without a degree four years before. Galileo was a brilliant teacher, but his radical ways of thinking and open criticism of Aristotle's teachings were not acceptable to the other professors at the university. They felt that he was too radical and that his teachings were not suitable. In 1592, his three-year contract was not renewed. .
1n 1592, he landed a job teaching mathematics at the University of Padua with the help of some aristocratic friends.