Pharmacology studies how drugs and other substances act on the body, testing dose, mechanism and effect experimentally rather than relying on the older descriptive tradition of materia medica, which catalogued remedies without explaining how they worked. The German physician Rudolf Buchheim founded the discipline in 1847 at the University of Dorpat, now Tartu in Estonia, building the first laboratory dedicated to experimental drug testing at his own expense in the basement of his home because the university would not yet fund one, and turning what had been a purely observational subject into an experimental science with reproducible results.
Traditions across the world attribute healing or visionary power to specific substances, and pharmacology is the discipline that can test what such a substance actually does in the body, distinguishing a documented pharmacological action from an effect a tradition attributes to it on spiritual or ritual grounds alone. The atlas draws on pharmacological findings wherever a healing, entheogenic or ritual substance's effect is described, citing what has actually been measured in a controlled dose response study rather than only what is traditionally claimed.