Galileo had the experience of beholding the heavens as they actually are for perhaps the first time, and wherever he looked he found evidence to support the Copernican system against the Ptolemaic, or at least weaken the authority of the ancients. This shattering experience-of observing the depths of the universe, of being the first mortal to know what the heavens are actually like-made so deep a an impression... that it is only by considering the events of 1609... that one can understand the subsequent direction of his life.