One of the earliest pioneers in the history of medicine, Muhammad ibn Zakariya al-Razi (also known by the Latinized version of his name, Rhazes or Rasis, 865–925 AD, 251–313 AH) was a Muslim Persian polymath, physician, and philosopher. He was born in the city of Rayy, near present-day Tehran, Iran, and spent most of his life between his birthplace and Baghdad, the capital city of the Abbasid caliphate. He taught medicine and was the chief physician in both cities. He made major and lasting contributions to the fields of medicine, music, philosophy, and alchemy and was the author of more than 200 books and treatises. This work is a selection of Al-Razi’s philosophical treatises. It discusses topics that include spiritual healing, metaphysics, divine knowledge, and concepts of time and place.