Published online by Cambridge University Press: 16 April 2018
Subsequent to the fifth century until modern times all theologians agreed that God the Trinity is constituted by three persons (in Boethius's sense of ‘an individual substance of a rational nature’) who have a common divine essence, and are individuated only by their relations to each other. Having that essence entailed each being omnipotent and so perfectly good. In virtue of his perfect goodness the Father necessarily produces the Son (in order to have one equal whom to love and be loved by) and the Spirit (in order that the Son have one equal other than the Father to love and be loved by). There cannot be more than three divine persons because three persons are sufficient for the existence of unselfish love, and so any fourth divine person would be produced by an act which none of the three needed to produce, and so would not exist necessarily and so could not be divine. Necessarily if there is one divine person, there are three and only three divine persons.