For example, the haselwort is reminiscent of the liver; thus, it must be beneficial for liver diseases; St John's wort Hypericum perforatum L. would be beneficial for treatment of wounds and stings given that the plant leaves appear as if they had been stung.
Paracelsus (1493-1541) was one of the proponents of chemically prepared drugs out of raw plants and mineral substances; nonetheless, he was a firm believer that the collection of those substances ought to be astrologically determined. He continuously emphasized his belief in observation, and simultaneously supported the “Signatura doctrinae”—the signature doctrine. According to this belief, God designated his own sign on the healing substances, which indicated their application for certain diseases. For example, the haselwort is reminiscent of the liver; thus, it must be beneficial for liver diseases; St John's wort Hypericum perforatum L. would be beneficial for treatment of wounds and stings given that the plant leaves appear as if they had been stung.