Isaac Newton

Alchemy, astrology and medicine (before the triumph of germ theory): three worthless intellectual systems which provided a good living for many into the 18th century and even beyond. Alchemy turned into chemistry; astrology was divorced by astronomy; and medicine (which might have become Pasteurism or Listerism) somehow kept its old name while abandoning all its old therapies. There have always been people with the good sense to say that alchemists and astrologers were charlatans, and doctors were more likely to kill you than cure you, but few listened. After all, all three could claim to be ancient, respectable forms of learning. And all three were too good to be true.

The question of why things fall has puzzled our species since we crawled out from the darkness of our primitive ignorance. Aristotle was the first to offer a serious theory. He proposed that each of the four elements (earth, air, fire, water) had a natural place to which it innately wanted to return. Fire and air rise because their place is in the heavens, whereas earth and water return to the Earth. Aristotelian philosophy had such a profound impact on human thought that this view prevailed for nearly 2,000 years. Only with the Renaissance and the ideas of Kepler and Galileo was it finally challenged; and only by standing on