Historically, Western medical ethics may be traced to guidelines on the duty of physicians in antiquity, such as the Hippocratic Oath, and early Christian teachings. The first code of medical ethics, "Formula Comitis Archiatrorum", was published in the 5th century, during the reign of the Ostrogothic king Theodoric the Great. In the medieval and early modern period, the field is indebted to Islamic scholarship such as Ishaq ibn Ali al-Ruhawi (who wrote the "Conduct of a Physician", the first book dedicated to medical ethics), Avicenna's Canon of Medicine and Muhammad ibn Zakariya ar-Razi (known as Rhazes in the West), Jewish thinkers such as Maimonides, Roman Catholic scholastic thinkers such as Thomas Aquinas, and the case-oriented analysis (casuistry) of Catholic moral theology. These intellectual traditions continue in Catholic, Islamic and Jewish medical ethics.