Prologomena -- Five theses -- Thesis 1 : God the Father neither made his own and only Son out of preexisting matter nor created him out of nothing, but from eternity generates him out of his own substance as consubstantial with himself -- Thesis 2 : The Holy Spirit, Lord and Life-giver, who proceeds from the Father and who spoke through the prophets, is to be adored and glorified together with the Father and the Son -- Thesis 3 : Thus, the Father and the Son and the Holy Spirit have one divinity, one power, one substance; they are, however, three hypostases or persons distinguished from one another by their proper attributes, which are relative; hence in God all things are one where there is no relational opposition -- Thesis 4 : The Holy Spirit proceeds from the Father and the Son as from one principle and by a single spiration -- Thesis 5 : The dogma of the Trinity, which is a mystery in the proper sense, cannot through natural human principles be either understood in itself or demonstrated from an effect. Even after revelation this remains true, although reason illumined by faith can, with God's help, progress towards some imperfect analogical understanding of this mystery.