The role of philosophy in Galen will be better understood through a consideration of the order of his own books which the author suggests to the aspiring doctor, a sort of ideal curriculum of study which at the same time implies an “order of knowledge”, a conceptual relationship between different intellectual areas, and is set out especially in My Own Books (Lib. Prop.) and The Order of My Own Books (Ord. Lib. Prop.); see Singer 2019b.