Galileo Galilei was born on 15 February 1564 in Pisa and was educated at the Camaldolese Monastery at Vallombrosa. In 1581 was sent by his father to enrol for a medical degree at the University of Pisa. Galileo never seems to have taken medical studies seriously, attending courses on his real interests which were in mathematics and natural philosophy. He left Pisa in 1585 without completing his medical degree and began teaching mathematics in Florence and later at Siena. During the summer of 1586 he taught at Vallombrosa, and in this year he wrote his first scientific book The little balance (La Balancitta) which described Archimedes’ method of finding the specific gravities of substances using a balance. His reputation grew and in 1588 he received a prestigious invitation to lecture on the dimensions and location of hell in Dante’s Inferno at the Academy in Florence. In 1589, Galileo was appointed to the Chair of Mathematics at the University of Pisa where he wrote De Motu a series of essays on the theory of motion which he never formally published. The book contains his important idea that one can test theories by conducting experiments and gave the famous example of testing falling bodies using an inclined plane to slow down the rate of descent.

In 1591, Vincenzo Galilei, Galileo’s father, died and as the eldest son Galileo had to provide financial support for the rest of the family. Being Professor of Mathematics at Pisa was not well paid, so Galileo lobbied for a more lucrative post. In 1592, Galileo was appointed Professor of Mathematics at the University of Padua (the University of the Republic of Venice) at a salary of three times that he had received at Pisa. On 7 December 1592 he gave his inaugural lecture and began a period …