The point had now been reached at which it was necessary to make some investigations of the senses in which those terms were used, which finally became classical and technical in the theological expression of Trinitarian doctrine. The first of these which needs to engage our attention is prosopon. Originally this word meant simply ‘face,’ and is sometimes expressly opposed to the sense of ‘mask’ as when Clement (paed. 3.2, 11.2) inveighs against those women who by painting their countenances made their prosopa into prosopeia. From this sense various others were derived, such as the expression indicated by a person’s face of his inner mind or motion, or the character to which he might wish to assume, or the role which he intended to act. In Origen, in particular, certain mental or moral associations are sometimes implied as pertaining to the character portrayed. Later, but apparently not before the fifth century, the word comes to mean ‘representative’ or ‘type’.
For such senses it comes to express the external being or individual self as presented to the onlooker, and of things, the expression of substance. It is fairly frequently used of particular individuals of a species, in much the same way as we speak of so many ‘head’ of cattle, or the ‘poll’ tax, and in this sense may be translated ‘person’ or ‘party.’ This usage is quite early, occurring in Clement of Rome (Cor. 1.1.1, “sedition which some few impetuous and rash prosopa had kindled,” cf. ib. 47.6); Ignatius (Magn. 6.1, “in the aforewritten prosopa I loved the whole multitude); Hippolytus (frag. in Balaam, Achelis p. 82 line 8, “it was necessary that Christ, as mediator between God and men, should receive a certain earnest from both, that He might be manifested as mediator between the two prosopa”); and elsewhere. And it persists to the end of the Patristic period, John of Damascus observing (dialectica 43) that a prosopon means whatsoever is evidenced by its own proper activities and characteristics, and that the holy Fathers referred to hypostasis (object) and prosopon (individual) and atomon (particular) to the same thing. Late writers use it with brutal impersonality of slaves; but from the time of Irenaeus it is used of inanimate objects in the sense of a distinct item (haer. 3.11.9), the question under discussion being whether the prosopa of the gospels might be either more or less that the orthodox four. Sometimes the qualitative aspect of the individual referred to is prominent especially in connection with the vice of ‘respecting persons’ (προσοποληψία), which (be it said) has nothing to do with regarding the exterior, but means showing partiality to some particular ‘individual;’ at other times the aspect which is uppermost is purely numerical.
Passing to theology, we find that the ‘face’ of God, to which various Old Testament texts refer, comes to be interpreted of Christ. As Clement puts it (paed. 1.7, 57.2), the face of God is the Logos, by whom God is illustrated and made known. A similar thought is repeated by later writers, the idea underlying the conception being that the Son is an objective presentation of the Father. Occasionally, it is the Holy Spirit who is so called, as by Cyril (thes. 34, 340c), who remarks that the Spirit is entitled the Face of the Father because He images forth, by means of His divine activity, the substance out of which He is.
The corresponding term persona is applied by Tertullian to the Persons of the Trinity, in the same sense of prosopon was commonly used in Greek. The ‘persona’ of the treatise against Praxeas is much more the concrete presentation of an individual than, as is commonly alleged, the holder of the legal title to a hereditament. Thus, we get such phrases as (ch. 7) “the Son acknowledges the Father, speaking in His own persona;” or (ib., arguing for the substantiality of the Son) “whatsoever therefore the substance of the Word was, that I call persona . . . and while I recognise the Son, I assert His distinction as second to the Father.” So again, after quoting various passages, Tertullian claims that they establish the existence of each several persona in its own special character (ch. II fin.); and remarks that is because the Father had at His side a second persona, His Word, and a third, the Spirit in the Word, that He said, as recorded in Genesis, “Let us make man in our image,” using the plural form (ib. 12).
Prosopon does not seem to have been used in Greek with reference to the Trinity earlier than by Hippolytus. In view of the relations previously shown to have existed between the thought of Hippolytus and that of Tertullian, it seems very probable that Hippolytus was the source from which the Latin contemporary adopted the term, though Hippolytus does not actually refer to three prosopa. But he does say (c. Noet. 7) that the use of the word ‘are’ in our Lord’s saying, “I and the Father are one,” must refer to two prosopa, though but to a single power. Again, he observes that he does not maintain the existence of two gods, but of one, though of two prosopa and a third economy, namely the grace of the Holy Spirit; for, he continues, the Father is one, but there are two prosopa because there is also the Son, and there is the third (τὸ δὲ τρίτον__does he mean third prosopon, or simply ‘the third item’?) the Holy Spirit.
The sense in which prosopon was in fact being used is shown in an interesting manner when he is criticising Callistus for his alleged adherence to the heresy of Noetus. After describing what he states to have been the doctrine of Callistus (ref. 10.27.4), his comment is: This then is one prosopon, distinguished in name, but not in substance.” By ‘substance’ (ousia) he here means, not generic character, but distinctive individuality, in the Aristotelian sense of ‘primary substance.’ Since therefore the Sabellians only admitted one such ‘primary substance,’ or concrete presentation, in the Godhead, according to Hippolytus they taught a doctrine of a single prosopon. In describing more fully the doctrine of Callistus, in an earlier passage (ref. 9.12.18-19), he had said that that element, according to Callistus, to which the name of the Son belonged, was simply the visible human nature, and that the divine human pneuma incarnate in this Son was really the Father, who united the manhood to Himself and deified it and made it one, so that the Father and Son can be called one God; the result, being single prosopon, cannot be two, and thus the Father suffered with the Son. Obviously, by prosopon Hippolytus meant not ‘mask’ but ‘individual.’
Origen is another of those who state that the Sabellians taught the doctrine of a single Person. His words only survive in the Latin translation, where persona is the term employed; but there is no reason to think that it represents anything other than prosopon in the lost original. They assert, he says (on Tit. ed. Ben. vol. 4 695B), that the subsistence of Father and Son is one and the same, that is to say, one persona underlying two names. Basil (hom. 24.1), Gregory Nazianzus and Chrysostom all say that the Sabellians reduced the Godhead to a single prosopon, though it appeared under three names. Eusebius, indeed, states (eccl. theol. 3.6.4) that Marcellus maintained one hypostasis triprosopos (one object with three faces); but the phrase belongs to Eusebius’ comment, not to Marcellus. Basil’s own comment and criticism, and had not been used by the Sabellians themselves. Nobody in fact seems to quote any such language as representing the form in which Sabellian doctrine had ever been actually taught, and most of the critics of Sabellianism positively state that those heretics denied the existence of three prosopa.
Until the middle of the third century, however, the term prosopon is sparingly used with reference to the Trinity in any sense. It is worth noticing that Origen appears to use it in the ordinary sense of individual presentation,though again the passage is only preserved in Latin. He writes (on Cant. 3, ed. Ben. vol 3, 84A) that the same being who in passage is called triad, on account of the distinction of personae, is in another called one God by reason of the unity of substance; and this statement is more noteworthy in that in this commentary Origen employs the word persona with some frequency in the sense of a character or speaker in a narrative or play. Eusebius revives its use in a rather different sense, observing (dem. en. 5.12.13) that in the Prophets, though a man audibly spoke, the oracle which he delivered was from God, who used him as His instrument, the prosopon who truly delivered the message being in some cases that of Christ, in others that of the Holy Spirit, and in others that of the supreme God.
However, the word does not pass into common use in Greek theology until the Arian controversy brought up the whole subject in acute form. From that point, while the writers who, like Athanasius, flourished before the ‘Cappadocian settlement,’ mainly avoided the use either of prosopon or hypostasis, and preferred to speak simply of ‘three’ and ‘one’, those who flourished later usually employed either term without prejudice or partiality. There does not seem to be any evidence whatever for the view that the term prosopon was ever discredited in orthodox circles at any period in theological development. On the contrary, it provided a convenient non-technical and non-metaphysical expression to describe the permanent and objective forms or Person in which the godhead is presented alike to human vision and to the divine self-consciousness.