Therefore the Father would be the same Person as the Son, but for the relation between them. The Persons are constituted by the relations. Were there no relations, God would be one Person; the three relations constitute three Persons.[1] So we come to the great axiom about the Blessed Trinity: "In God all things are one, except where there intercedes the opposition of a relation" — Omnia sunt unum, ubi non obviat relationis oppositio.[2] Now exactly the same principle applies also to the Holy Ghost. The Holy Ghost is God, is identified with every perfection of the simple essence of God. He cannot be distinguished from the other Persons by anything absolute or positive (otherwise he would either have something they have not, or lack something they have, and there would be a limitation in God). He is distinguished from God the Father only by the mutual relation of "Spiratio," or Procession. He proceeds from the Father, and so is distinguished from him. If he did not, he would be the same Person as the Father. And he proceeds also from the Son. If he did not, there would be no relation between them, and so, again, he would be identified with God the Son. The only way in which there can be three really distinct Persons in the Blessed Trinity is that there is a real relation between each of them — Paternity between the first and second, Procession between first and third, and Procession also between second and third. So, from the point of view of scholastic theology, the thesis of the Latin schoolmen is unanswerable: "The Holy Ghost proceeds from the Father and the Son; indeed, if he did not proceed from the Son, he would not be distinct from him. Wherefore the error of the Greeks in this matter fundamentally overturns the truth of the Trinity."[3] The Orthodox look at the whole
1 The right way to say this is that the Persons are subsistent relations.
2 This was the definition at Florence, Decretum pro Jacobitis, Denzinger, p. 598.
3 Bilot, o.c. thesis 26. All this reasoning will be found in St. Thomas, Summa theol. p. i. qu. iii. art. 7, qu. xxviii.-xxx. xxxvi. He also uses it against the Greeks continually, cf. opusc. i. contra errores Græcorum, &c. The clearest possible exposition of the whole system is Billot, de Deo trino, passim, especially the præviæ disputationes, de processionibus (pp. 319-338), de relationibus (pp. 371-387), de personis (pp. 422-428).
