​HYPOSTASIS, in theology, a term frequently occurring in the Trinitarian controversies of the 4th and 5th centuries. According to Irenaeus (i. 5, 4) it was introduced into theology by Gnostic writers, and in earliest ecclesiastical usage appears, as among the Stoics, to have been synonymous with oboia. Thus Dionysius of Rome (cf. Routh, Rel. Sacr. iii. 373) condemns the attempt to sever the Godhead into three separate hypostases and three deities, and the Nicene Creed in the anathemas speaks of ​ii érépas iP7|'00'Té.d'6¢:)$ fi otimfas. Alongside, however, of this persistent interchange there was a desire to distinguish between the terms, and to confine l§ 7l'60'TU.0'L§ to the Divine persons. This tendency arose in Alexandria, and its progress may be seen in comparing the early and later writings of Athanasius. That writer, in view of the Arian trouble, felt that it was better to speak of oboia as “ the common undifferentiated substance of Deity, ” and O1rb<11'ao'Ls as “ Deity existing in a personal mode, the substance of Deity with certain special properties ” (ouoia. pe-ré. -rwwv iétw/.uirwz/). At the council of Alexandria in 362 the phrase rpefs l>7l'O0'Td0'6LS was permitted, and the work of this council was supplemented by Basil, Gregory of Nazianzus and Gregory of Nyssa in the formula pta. oboia., 1-pei; l§ 1|"00'T6.0'€L§ or /, Jia oilaia. év 'rpiow lbroaréoeucv.

The results arrived at by these Cappadocian fathers were stated in a later age by John of Damascus (De orth. fid. iii. 6), quoted in R. L. Ottley, The Doctrine of the Incarnation, ii. 257.