Complex sentence: According to his biography, he went to Toledo, Spain, studied black magic there, returned home to become a Benedictine monk at St Samer Abbey near Calais, and then left the monastery to avenge his murdered father.
Split into simpler sentences: According to his biography, he went to Toledo, Spain, studied black magic there. ' He then returned home to become a Benedictine monk at St Samer Abbey near Calais, and then left the monastery to avenge his murdered father.