In order to understand the influence of Basil on the doctrine and the resulting attitude of Gregory of Nyssa in the polemic against Apollinaris, starting from Basil's letters is necessary. In the Ep. 129, written in 373, the Cappadocian associates for the first time the name of Apollinaris with Sabellius. The couple Apollinaris-Sabellius recurs also in other letters (cfr. Ep. 224 and 265) and constitutes one of the guidelines used by Basil to defend himself from the charges of being a friend of the bishop of Laodicea and of sharing his audacious doctrine. On the other hand his second defensive strategy consists of portraying Apollinaris as supporter of fabulous theories, which are not based on the Scriptures, and of Judaizing ideas, according to which Christ's teachings will be abrogated by the precepts of the law (cfr. Ep. 263 and 265). Generally, Basil prefers to distance himself from Apollinaris and does not intervene on the theological problems raised by him.
Few years after his brother, Gregory instead takes a clear stand on the theological debate and reveals the ambiguities and the inconsistencies of the Apollinaris' arguments. Gregory tries to unmask the absurdities of the opponents' theories starting with the correct interpretation of the scriptural passages used by Apollinaris. Therefore, the first aim of this study is to compare the exegesis developed by Basil and Gregory in relation to the passages at issue. Secondly, the attention will be focused on the lexicon and phrases used by Basil and Gregory to define the union of the human and divine natures of Christ. Finally, by setting the research in the historical and cultural context, it will be possible to reconstruct a more articulated pattern of the polemic.