Historically, Western healthcare ethics may be traced to guidelines on the duty of physicians in antiquity, such as the Hippocratic Oath, and early rabbinic and Christian teachings. The initial code of medical ethics, Formula Comitis Archiatrorum, was published within the 5th century, throughout the reign of the Ostrogothic king Theodoric the Great. In the medieval and early modern period, the field is indebted to Muslim medicine including Ishaq bin Ali Rahawi (who wrote the Conduct of a Doctor, the first book dedicated to health-related ethics) and Muhammad ibn Zakariya ar-Razi (recognized as Rhazes in the West), Jewish thinkers for example Maimonides, Roman Catholic scholastic thinkers for example Thomas Aquinas, and also the case-oriented analysis (casuistry) of Catholic moral theology. These intellectual traditions continue in Catholic, Islamic and Jewish health-related ethics.