Here the vocabulary of unity in the person of Christ: parsupa (person) and apay (face). Prosopon-person according to the post-Chalcedon Greek definition is the appearance of a hypostasis-person. It is the face and external appearance. Again, the Church of the East uses a different definition.
In the Church of the East, the parsupa (person or prosopon) is the ontological whole of the being - the Syriac word “apay” (face) describes the outward appearance. Hence, when the Greek of II Cor 4.6 is translated: “For it is the God who commanded light to shine out of darkness, who has shone in our hearts to give the light of the knowledge of the glory of God in the prosopon of Jesus Christ”, it is understood as “face of Jesus Christ”. But from the Peshitta’s Syriac, which has parsupa exactly where the Greek has prosopon, it is understood as “person of Jesus Christ”. Here are some quick definitions which will be supported by the quotes that follow.
Parsupa (Person; Syriac version of Prosopon): a person fully enfleshed. The complex reality of an individual as an expression of his qnuma-nature. Apay (Face): the outward appearance of a person. The face and manifestation of the person.
For our definition of parsupa and apay, let us reference Mar Yokhannan Bar Zo’by’s The Book of Harmonious Texture. The section I quote from is titled “On the difference between Kyana and Qnuma: and Qnuma from Parsupa: and Parsupa from Apay.” The title already lends itself to an understanding of these four words, but Mar Yokhannan has more to offer (translation mine): Now on person, that person is different from qnuma. Parsopa is different from qnuma in that it possesses qualities, such as beauty, hatefulness, ugliness or darkness. But qnuma has only one attribute because it is singular [ie, a particular instance of a general nature]. But a person has many [attributes or qualities] because it is a multitude of charicteristics such as being the son of so and so, beautiful or ugly. These things pertain to parsopa, which is the formation or type (yuqna) of the qnuma.” (ܡܪܓܢܝܬܼܐ ܕܥܠ ܫܪܪܐ ܕܟܪܣܛܝܢܘܬܐ.ܩܫ ܝܘܣܦ ܒܝܬ ܩܠܝܛܐ ܡܘܨܠ ܡܛܒܥܬܐ ܐܬܘܪܝܬܐ 1924 pg 99)
Then, to complete our new Syriac terms, Mar Yokhannan gives us the difference between parsopa-person and apay-face: “Now on person, that person is different than face in that it does not present the concrete image to the mind. The face is the appearance, but the person is not the concrete outer form.”( ܡܪܓܢܝܬܼܐ pg 99)
To summarize: qnuma is only the reality of a nature, but when we want to speak of characteristics or expressions that come from the qnuma, then we move into speaking of a parsupa. Parsupa is very much what we think of as a person or individual, except that in Syriac, we distinguish the outer form with a different word: apay or face. For example, I am an instance of human kyana, so I have a human qnuma (simply human nature vis-à-vis a body, soul and spirit) which is evident in that it expresses a parsopa-person which is depicted in my apay-appearance.