"filiation," and "procession." Of these only four are relations, for "innascibility" is not a relation, except by reduction, as will appear later ( Question [33], Article [4], ad 3). Four only are properties. For "common spiration" is not a property; because it belongs to two persons. Three are personal notions---i.e. constituting persons, "paternity," "filiation," and "procession." "Common spiration" and "innascibility" are called notions of Persons, but not personal notions, as we shall explain further on ( Question [40], Article [1], ad 1).
Reply to Objection 1: Besides the four relations, another notion must be admitted, as above explained.
Reply to Objection 2: The divine essence is signified as a reality; and likewise the persons are signified as realities; whereas the notions are signified as ideas notifying the persons. Therefore, although God is one by unity of essence, and trine by trinity of persons, nevertheless He is not quinary by the five notions.
Reply to Objection 3: Since the real plurality in God is founded only on relative opposition, the several properties of one Person, as they are not relatively opposed to each other, do not really differ. Nor again are they predicated of each other, because they are different ideas of the persons; as we do not say that the attribute of power is the attribute of knowledge, although we do say that knowledge is power.
Reply to Objection 4: Since Person implies dignity, as stated above ( Question [19], Article [3]) we cannot derive a notion of the Holy Spirit from the fact that no person is from Him. For this does not belong to His dignity, as it belongs to the authority of the Father that He is from no one.
Reply to Objection 5: The Son and the Holy Ghost do not agree in one special mode of existence derived from the Father; as the Father and the Son agree in one special mode of producing the Holy Ghost. But the principle on which a notion is based must be something special; thus no parity of reasoning exists.
Whether it is lawful to have various contrary opinions of notions?
Objection 1: It would seem that it is not lawful to have various contrary opinions of the notions. For Augustine says (De Trin. i, 3): "No error is more dangerous than any as regards the Trinity": to which mystery the notions assuredly belong. But contrary opinions must be in some way erroneous. Therefore it is not right to have contrary opinions of the notions.
Objection 2: Further, the persons are known by the notions. But no contrary opinion concerning the persons is to be tolerated. Therefore neither can there be about the notions.
On the contrary, The notions are not articles of faith. Therefore different opinions of the notions are permissible.
I answer that, Anything is of faith in two ways; directly, where any truth comes to us principally as divinely taught, as the trinity and unity of God, the Incarnation of the Son, and the like; and concerning these truths a false opinion of itself involves heresy, especially if it be held obstinately. A thing is of faith, indirectly, if the denial of it involves as a consequence something against faith; as for instance if anyone said that Samuel was not the son of Elcana, for it follows that the divine Scripture would be false. Concerning such things anyone may have a false opinion without danger of heresy, before the matter has been considered or settled as involving consequences against faith, and particularly if no obstinacy be shown; whereas when it is manifest, and especially if the Church has decided that consequences follow against faith, then the error cannot be free from heresy. For this reason many things are now considered as heretical which were formerly not so considered, as their consequences are now more manifest.
So we must decide that anyone may entertain contrary opinions about the notions, if he does not mean to uphold anything at variance with faith. If, however, anyone should entertain a false opinion of the notions, knowing or thinking that consequences against the faith would follow, he would lapse into heresy.
By what has been said all the objections may be solved.
OF THE PERSON OF THE FATHER (FOUR ARTICLES)
We now consider the persons singly; and first, the Person of the Father, concerning Whom there are four points of inquiry:
(1) Whether the Father is the Principle?
(2) Whether the person of the Father is properly signified by this name "Father"?
(3) Whether "Father" in God is said personally before it is said essentially?
(4) Whether it belongs to the Father alone to be unbegotten?
Whether it belongs to the Father to be the principle?
Objection 1: It would seem that the Father cannot be called the principle of the Son, or of the Holy Ghost. For principle and cause are the same, according to the Philosopher (Metaph. iv). But we do not say that the Father is the cause of the Son. Therefore we must not say that He is the principle of the Son.
Objection 2: Further, a principle is so called in relation to the thing principled. So if the Father is the principle of the Son, it follows that the Son is a person principled, and is therefore created; which appears false.
Objection 3: Further, the word principle is taken from priority. But in God there is no "before" and "after," as Athanasius says. Therefore in speaking of God we ought not to used the term principle.
On the contrary, Augustine says (De Trin. iv, 20), "The Father is the Principle of the whole Deity."
I answer that, The word "principle" signifies only that whence another proceeds: since anything whence something proceeds in any way we call a principle; and conversely. As the Father then is the one whence another proceeds, it follows that the Father is a principle.
Reply to Objection 1: The Greeks use the words "cause" and "principle" indifferently, when speaking of God; whereas the Latin Doctors do not use the word "cause," but only "principle." The reason is because "principle" is a wider term than "cause"; as "cause" is more common than "element." For the first term of a thing, as also the first part, is called the principle, but not the cause. Now the wider a term is, the more suitable it is to use as regards God ( Question [13], Article [11]), because the more special terms are, the more they determine the mode adapted to the creature. Hence this term "cause" seems to mean diversity of substance, and dependence of one from another; which is not implied in the word "principle." For in all kinds of causes there is always to be found between the cause and the effect a distance of perfection or of power: whereas
