Galileo Galilei.

Galileo Galilei (1564–1642) has always played a key role in any history of science and, in many histories of philosophy, he is a, if not the, central figure of the scientific revolution of the 17th century. His work in physics or natural philosophy, astronomy, and the methodology of science still evoke debate after over 360 years. His role in promoting the Copernican theory and his travails and trials with the Roman Church are stories that still require re-telling. Galileo and his family moved to Florence in 1572. He started to study for the priesthood, but left and enrolled for a medical degree at the University of Pisa. He never completed this degree, but instead studied mathematics notably with Ostilio Ricci, the mathematician of the Tuscan court. Later he visited the mathematician Christopher Clavius in Rome and started a correspondence with Guildobaldo del Monte. He applied and was turned down for a position in Bologna, but a few years later in 1589, with the help of Clavius and del Monte, he was appointed to the chair of mathematics in Pisa.In 1623 Galileo published The Assayer dealing with the comets and arguing they were sublunary phenomena. In this book, he made some of his most famous methodological pronouncements including the claim the book of nature is written in the language of mathematicsn 1634, while Galileo was under house arrest, his daughter, Maria Celeste died. At this time he began work on his final book, Discourses and Mathematical Demonstrations concerning Two New Sciences. This book was smuggled out of Italy and published in Holland. Galileo died early in 1642.