If you read a about the history of science, you will no doubt be astonished by some of the amazing theories that people used to believe. I recently finished reading The Invention of Science by David Wootton, which documents many of them (and is well worth reading, not just because of this!) For example, did you know that if you put garlic on a magnet, the magnet will stop working? Fortunately, you can recover the magnet by smearing goats blood on it. Giambattista della Porta tested this and c...