The Symbolum Quicunque [Athanasian Creed] is a remarkably clear and precise summary of the doctrinal decisions of the first four œcumenical Councils (from A.D. 325 to A.D. 451), and the Augustinian speculations on the Trinity and the Incarnation. Its brief sentences are artistically arranged and rhythmically expressed. It is a musical creed or dogmatic psalm…The first part (ver. 3–28) sets forth the orthodox doctrine of the Holy Trinity, not in the less definite Athanasian or Nicæno-Constantinopolitan, but in its strictest Augustinian form, to the exclusion of every kind of subordination of essence…The second part (ver. 29–44) contains a succinct statement of the orthodox doctrine concerning the person of Christ, as settled by the general Councils of Ephesus 431 and Chalcedon 451, and in this respect it is a valuable supplement to the Apostles’ and Nicene Creeds. It asserts that Christ had a rational soul (νοῦς, πνεῦμα), in opposition to the Apollinarian heresy, which limited the extent of his humanity to a mere body with an animal soul inhabited by the divine Logos. It also teaches the proper relation between the divine and human nature of Christ, and excludes the Nestorian and Eutychian or Monophysite heresies, in essential agreement with the Chalcedonian Symbol.
Philip Schaff, The Creeds of Christendom, (New York: Harper & Brothers, Publishers, 1878), 1.37, 39.