Trinitarian and Christological Context of Aquinas’ Statements about the Person

Aquinas frequently (forty times) refers to boethian definition of person: rationalis naturae individua substantia. He uses such notion in trinitarian, christological and anthropological contexts. We find this definition in relationship with main faith principles about Trinity and Incarnation, depending on the Magisterium of Lateranense IV and the great christological councils. The use of boethian definition may be count among the preambula fidei and it is relevant both for theology and philosophy