Complex sentence: He wrote a history of the Arian controversy titled "History of the Church", of which only an epitome by Photius survives, as well as a treatise against Porphyry, which is lost.
Split into simpler sentences: He wrote a history of the Arian controversy titled "History of the Church", of which only an epitome by Photius survives. He also wrote a treatise against Porphyry, which is lost.