The clavis sanationis was written by Simon of Genoa, a physician to pope Nicolas IV. It is a thirteenth century medical dictionary written in Latin that uses, and often quotes, a number of valuable sources which are otherwise lost today, explaining medical terminology and translating it into Arabic and Greek.
Most entries would have the following structure: “The disease/plant v is called w in Arabic and x in Greek. According to source y it is defined by z”. In several cases, source y would have been lost in the course of the centuries.
The most obvious value of the clavis is reconstructing lost sources. Also, it allows us to understand which type of content was considered relevant at the time, and which sources Simon had at his disposal. Moreover, the text yields large amounts of new lexicographical material. It is a missing link that will help us to connect the Latin, Greek and Arabic tradition.