. . According to legend, Galileo’s new passion began with a chandelier. He observed the massive lamp in the cathedral swinging in the breeze. How many thousand millions -- of visions had seen this before and never given it a second thought? For some reason Galileo decided to time the motion (using his own pulse as a clock). What he discovered was that, no matter how long or short the arc, the natural pendulum took the same time to complete it. The story may be apocryphal but it points us to two fundamentals of Galileo’s mature thinking: the process began with observation and it could be understood with the aid of mathematics. ~ Page 132