When he finally acquired a career as a cleric, he took an active part in the theological controversies between the Eastern Orthodox Church and the Roman Catholic Church, writing treatises on the Procession of the Holy Spirit, advocating the western usage. He was the tutor of the learned Theodore II Laskaris of the Nicaean Empire, and a great collector of classical texts.
There, he received a liberal education in Prusa, Nicaea, Smyrna and Scamander. Blemmydes studied medicine, philosophy, theology, mathematics, astronomy, logic, and rhetoric.