The author of this treatise, Isma‘īl ibn Muhammad al-Husayn al-Jurjānī (circa 1042–1136), also known as al-Sayyid Isma‘īl, was one of the most-famous physicians and prolific writers on medicine of his time. He was a student of the noted Persian physician Ibn Abī Sādiq Al-Nīšapūrī, who followed the teachings of Ibn Sīnā (Avicenna) and was nicknamed Buqrāt al-tāni (The second Hippocrates). Thanks to his proficiency in medicine, al-Jurjānī was employed by the shahs of Khvarazm, Qutb al-Dīn Muhammad (1097–1127) and ‘Azīz b. Muhammad (1127–56). The former commissioned him to compose a monumental medical encyclopedia in Persian, which became Zakhīrah-i Khvārazm’Shāhī (The treasure of Khvarazm’Shah). The tenth part of that work, on medicines both simple and compound, sometimes circulated as a separate treatise: Kitāb-i Qarabadhin, or Dakīra (The formulary), used by the shahs on their travels. The Kitāb Zubdat al-Tibb (The quintessence of medicine) is another al-Jurjānī medical manual, of which not many copies survive. This one is a very elegant and richly rubricated 17th-century manuscript. The first part of Zubdat al-Tibb is a treatise on theoretical medicine arranged in the form of tables, aimed at schematizing the diagnoses that can be made from analyses of the pulse and urine. In what follows, al-Jurjānī deals with human anatomy and the treatment of fevers. This large manuscript—a true compendium of the medical knowledge available to a 12th-century physician—includes other treatises by Al-Jurjānī devoted to the explanation of simple and composite drugs and to discussions of tumors, sexual intercourse and sexually transmittable illnesses, and poisons.