cf. Letters xxxviii. and xcii.  Basil is anxious to show that his own view is identical with the Nicene, and does not admit a development and variation in the meaning of the word hypostasis; but on comparing such a passage as that in Athan. c. Afros, “hypostasis is substance, and means nothing else but very being” (ἡ δὲ ὑπόστασις οὐσία ἐστὶ καὶ οὐδὲν ἀλλὸ σημαινόμενον ἔχει ἢ αὐτὸ τὸ ὄν) with St. Basil’s words in the text it appears plain that hypostasis is not used throughout in the same sense.  An erroneous sense of “three hypostases” was understood to be condemned at Nicæa, though Athanasius, e.g. “In illud omnia,” etc., Schaff and Wace’s ed., p. 90, does himself use the phrase, writing probably about ten years after Nicæa; but he more commonly treats ουσία and ὑπόστασις as identical.  See specially the Tomus ad Antiochenos of a.d. 362 on the possible use of either “three hypostases” or “one hypostasis.”  cf. also n. on p. 179.