The great physicians of the past wrote treatises on the therapeutic use of simples. Not only plants, but also drugs; not only botany, but also materia medica. The most famous works are those of Theophrastus (371-287 BC ca), Dioscorides (first century AD) and Galen (130-200 ca). The Arab School developed the most advanced knowledge of the time and spread it through translations of texts and new discoveries, with Mesue (777-857), Rhazes (864-925) and Avicenna (980-1037). The Salerno School followed this tradition in its cures, combing a knowledgeable use of herbs.
With Humanism and the Renaissance, ancient knowledge was revisited with a modern, scientific spirit. There was a need to identify medical plants with certainty in order to avoid the risks of erroneous identification and adulteration. Illustration became a precious instrument for the botanical determination of species. Different versions of texts and medicaments were compared. Printing provided an instrument to share the knowledge. Botanical gardens sprang up at the same time and in the same context of confronting theory with experimentation. University lectures on medicinal plants, simples, had a theoretical framework that illustrated the works of the great authors, but uncertainties about the identification of the plants mentioned in the classical texts remained. Botanical gardens were created to provide support to the theoretical part of the lectura simplicium, lessons on simples, with live observation, ostensio simplicium. In 1533, in Padua, the lectura simplicium was entrusted to Francesco Buonafede and, in 1543, the lecturer requested the Riformatori dello Studio to create a Horto medicinale, "in which there should also be a ‘spezieria’", an apothecary (Cappelletti p. VII).
The path towards scientific definitions of simples would have to wait for progress on systematic botany, which Linnaeus put a full stop to in the eighteenth century, and chemistry, which, after the seventeenth-century boost from Paracelsus, reached its peak in the following century.