By most historical accounts, the Roman Emperor Caligula was a nightmare–a sadistic, debaucherous, and unstable despot. According to a study published in the Proceedings of the European Academy of Sciences and Arts, Caligula was also fond of learning about medicinal plants. Ruling Rome from only 37 to 41 CE, historical accounts indicate that the young Roman Emperor managed to pack an impressive amount of cruelty, debauchery, and bizarre edicts into reign. According to the 2nd century text, an unknown Roman senator who rose to the high rank of praetor once requested that Caligula grant him a leave of absence due to an undescribed ailment. Furthermore, how did the doomed senator and Caligula already know about them?