In 1633 (9 years before his death), Galileo was forced to kneel before his inquisitors and apologize for his work that had shown the sun to be the center of the universe. After that, he was put under house arrest in Florence, where he was bedridden most of the time because of asthma and painful ruptures. In 1638, his Discourses were finished and published in Holland, out of the reaches of the Catholic Church. He then went blind and was relatively helpless. From his bed, he continued to teach and dictate Discourses, particularly to his two faithful students, Vincenzo Viviani and Evangelista Torricelli. During this time, his interest in the motion of bodies led him to study the relationships between the speed of a falling body, the distance it falls and the time it takes. Using his findings from his experiments in Discourses, he was able to conclude that the trajectory of weapons, cannon balls for instance, took the form of a parabola—a theory new to his contemporaries and yet proven by Galileo by experimentation. It was during these bedside lessons on Galileo’s Discourses that Torricelli got his idea for the mercury barometer. In November 1641 Galileo became very ill with a fever and kidney complaint and on January 8 of the next year, he died at the age of seventy-seven. His work lives on in the methodologies of experimental science, in astronomy and in many other scientific and mathematical disciplines.
In it he argues that truth is found through observation, not through endless contemplation of what is written in the Bible. The way in which he makes his argument is adroit. He affirms the infallibility of scripture and then confronts the case where the learned books of worldly authors seem to contradict scripture. The theological authorities, he says, should make a distinction between “propositions about nature which are truly demonstrated and others which are simply taught”. In the former case they must confine themselves to showing that there is no real disagreement; that is, they must give an interpretation of scripture that makes room for that which has been demonstrated by scientific observation and reasoning. It is only in the latter case that scripture has primacy, in the case where propositions are “simply taught”.