Historically, Western medical ethics could possibly 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, during the reign on the Ostrogothic king Theodoric the Great. Within the medieval and early contemporary period, the field is indebted to Muslim medicine for example Ishaq bin Ali Rahawi (who wrote the Conduct of a Physician, the first book dedicated to medical ethics) and Muhammad ibn Zakariya ar-Razi (known as Rhazes within the West), Jewish thinkers like Maimonides, Roman Catholic scholastic thinkers for example Thomas Aquinas, along with the case-oriented analysis (casuistry) of Catholic moral theology. These intellectual traditions continue in Catholic, Islamic and Jewish healthcare ethics.