There are two views on the origin of syphilis: that Columbus's sailors brought it from the New World, and that Europeans had known the disease since ancient times

Each version has its evidence: the first epidemic of syphilis did indeed break out after the American expedition, yet diseases resembling syphilis are described by Cornelius Celsus, Claudius Galen and Avicenna, and besides there have been finds of afflicted Neolithic bones.

Be that as it may, similar diseases were treated from antiquity right up to the twentieth century with mercury ointment. Henry VIII used it, and so did Francis I. All that changed was that in time physicians learned to choose the dosage and the mercury content more carefully.

It is all very interesting, of course, who fell ill, when and how, but even more curious is why the medieval leeches, in their struggle against the unmentionable malady, settled on mercury in particular. The explanation was purely alchemical: the disease is venereal in nature and comes from Venus; Venus is opposed by Uranus, and Uranus is mercury.

In my view, an excellent example of how the verification of a theory does not necessarily make it true. One may proceed from wholly false premises and yet arrive at the correct solution!