A fun anecdote from the history of medicine. (Fun in hindsight, though not necessarily fun for those who lived through the medical history.)
The late-medieval Iatrochemists believed that progress could be made by uniting medicine with alchemy. Their intellectual leader was Paracelsus (1493-1541), a Swiss physician whose goal was to reform medical chemistry by rejecting reliance on traditions based on ancient texts. Symbolically, Paracelsus inaugurated his lecture series at Basel by burning the books of Galen and Avicenna. Alchemy, in turn, was a hybrid practice of experimental chemistry and astrology.
A perfect example of iatrochemical theory in action was the mystery of anemia: Why did iron salts cure it? Practicing physicians knew that it did, but nobody had a good theory explaining why.
So here’s the iatrochemical explanation. Anemia, we believe, is a matter of having weak blood. Clearly, the weak blood needs to be strengthened, which iron salts do, but how? Let’s start with the fact that iron is hard and strong. That is why we use iron to make weapons of war. The Roman god for war is Mars. Mars is also the red planet — and we know that blood is red. Quod erat demonstrandum has been achieved: the strength of iron is astrologically communicated through Mars to the redness of the blood, thereby curing the anemia.
(Up next: How Venus makes those love potions work. Ever notice that Venus and Viagra start with the same letter? Coincidence?)