SUMMARY: There are two ways in which the constitution of the divine Persons are more closely defined: the relation of one Person to both others and the mode of existence of the same Person. In this article, John Damascene, who follows the example of the Cappadocian Fathers, is shown as placing the primary emphasis on the mode of existence. But since the theology of the Latins is commonly enough supposed to make more of the mutual relation, which St. Thomas accurately described as subsistence, it is important to know the reason why, alongside the school of St. Tho­mas, which followed the teaching of St. Anselm of Canterbury in this matter, there existed a Fran­ciscan school, which - led by Richard of St. Victor in developing the previous notion of St. Au­gustine - is seen to accord with the theological custom the Greek Fathers.