Today one in four pharmaceuticals are derived from plants. A hundred years ago virtually all drugs were derived from plants. A knowledge of medicinal botany was crucial to medical practicioners in those days. Al-Idrisi 1099-1166 was a muslim scholar born in Ceuta in Morocco. His finest contribution is perhaps his book of drugs. Kitab al-Jami-li-Sifat Ashtat al-Nabatat. This summarised all the available knowledge about medicinal plants. This work in the Kingdom of Sicily and Southern Italy established by the Normans led to a renaissance in western understanding. Based for much of his career in Palermo in Sicily Al-Idrisi is famous for 'The Book of Roger' an encyclopedia of known geography describing all the known regions of the world with great accuracy. Sicily at this time was a great meeting point of Greek, Christian and Islamic culture and important trading hub. Lemon and citrus cultivation on Sicily was extended greatly by the jesuits in the seventeenth century but introduced to sicily in the time of Al-Idrisi. Besides the better known virtues and uses of lemons in cooking, fragrance, hygiene and aromatherapy, the lemons ph of 2-3 made it a safe and effective contraceptive.