How were the medicinal properties of herbs discovered?

How were the medicinal properties of herbs discovered?

Herbal remedies have been used since the beginning of time. The Ebers Papyrus, dating from the 16th century BC, lists no less than 700 herbal remedies, including poppy, castor oil etc. In the first century AD, Pedanius Dioscorides listed over 500 plants in his De Materia Medica, which was still used in the 17th century.