In the 1600s a doctor named Thomas Browne wrote a comprehensive refutation of many of the superstitions of his day. This has recently been published online.

Some of the propositions he refutes:

• The common Tenent, that Crystall is nothing else but Ice strongly congealed.
• That bitter Almonds are preservatives against Ebriety.
• That an Elephant hath no joints.
• That Iews stinke.
• Concerning the beginning of the world, that the time thereof is not precisely knowne, as commonly it is presumed.

You get the idea. This book is amazing.