What came about in bodily form in Mary, the fullness of the godhead shining through Christ in the Blessed Virgin, takes place in a similar way in every soul that has been made pure. The Lord does not come in bodily form, for ‘we no longer know Christ according to the flesh’, but he dwells in us spiritually and the Father takes up his abode with him, the Gospel tells us. In this way the child Jesus is born in each one of us.
GREGORY OF NYSSA On Virginity (PG 46, 324 & 838)
In order that the dispositions of the Gospel and the things of the Holy Spirit may develop in us, their author has to be born in us.
GREGORY OF NYSSA Against Eunomius (PG 45, 585)