Now Vincenzio himself, as shown in his writings on musical theory, had a rooted objection to taking things on trust, so it is not surprising that Galileo found himself continually at issue with his teachers in philosophy, and thus early struck the keynote of his stormy career. What passed for philosophy in those days had degenerated almost entirely into blind repetition of the statements and doctrines of ancient philosophers, and particularly of Aristotle. But Aristotle and the Greek philosophers generally were not accustomed to put their highly speculative theories to the test of actual experiment, however easy and obvious such experiment might be. They contented themselves with discussions as to what ought to happen according to their preconceived notions of physical laws, rarely attempting to see what does actually happen. Galileo's mind worked in a very different way, and refused to bind or blind itself in such a manner, so he promptly questioned what appeared to be doubtful statements and did not hesitate to contradict if he felt he had a clear case against them. He soon gained such notoriety in this way that he was nicknamed the Wrangler by his fellow-students, and heartily disliked by the professors, who were not only sticklers for tradition, but probably found it less troublesome to rely on memory than on intelligence.
In what we should call his Freshman's term Galileo made his first notable discovery. In the Cathedral of Pisa he noticed a lamp swinging suspended from the roof, and remarked that as the swings died away they did not seem to get slower or quicker. He tested this by counting his pulse-beats, having no other means at hand for measuring time, and found the time of swing to be practically constant. He at once saw that the rule would work both ways, and that a swinging weight would provide a check on the regularity of the pulse, a matter of
