In 1921, Imam Khomeini commenced his studies in Arak. The following year, Ayatollah Haeri-Yazdi transferred the Islamic seminary to the holy city of Qom, and invited his students to follow. Imam Khomeini accepted the invitation, moved, and took up residence at the Dar al-Shafa school in Qom before being exiled to the holy city of Najaf in Iraq. After graduation, he taught Islamic jurisprudence (Sharia), Islamic philosophy and mysticism (Irfan) for many years and wrote numerous books on these subjects. Although during this scholarly phase of his life Imam Khomeini was not politically active, the nature of his studies, teachings, and writings revealed that he firmly believed from the beginning in political activism by clerics. Three factors support this suggestion. First, his interest in Islamic studies surpassed the bounds of traditional subjects of Islamic law (Sharia), jurisprudence (Fiqh), and principles (Usul) and the like. He was keenly interested in philosophy and ethics. Second, his teaching focused often on the overriding relevance of religion to practical social and political issues of the day. Third, he was the first Iranian cleric to try to refute the outspoken advocacy of secularism in the 1940s. His now well-known book, Kashf-e Asrar (Discovery of Secrets) was a point by point refutation of Asrar-e Hezar Saleh (Secrets of a Thousand Years), a tract written by a disciple of Iran's leading anti-clerical historian, Ahmad Kasravi. Also he went from Qom to Tehran to listen to Ayatollah Hassan Modarres —the leader of the opposition majority in Iran's parliament during 1920s. Imam Khomeini became a Marja in 1963, following the death of Grand Ayatollah Seyyed Hossein Borujerdi (Source: Khamenei.ir).