For that which is peculiar to all
flesh is acknowledged also in the case of that flesh, namely, that that Body
too was maintained by bread; which Body also by the indwelling of God the Word
was transmuted to the dignity of Godhead. Rightly, then, do we believe that now
also the bread which is consecrated by the Word of God is changed into the Body
of God the Word. For that Body was once, by implication, bread, but has been
consecrated by the inhabitation of the Word that tabernacled in the flesh.
Therefore, from the same cause as that by which the bread that was transformed
in that Body was changed to a Divine potency, a similar result takes place now.
For as in that case, too, the grace of the Word used to make holy the Body, the
substance of which came of the bread, and in a manner was itself bread, so also
in this case the bread, as says the Apostle, "is sanctified by the Word of
God and prayer"; not that it advances by the process of eating to the
stage of passing into the body of the Word, but it is at once changed into the
body by means of the Word, as the Word itself said, "This is My
Body." Seeing, too, that all flesh is nourished by what is moist (for
without this combination our earthly part would not continue to live), just as
we support by food which is firm and solid the solid part of our body, in like
manner we supplement the moist part from the kindred element; and this, when
within us, by its faculty of being transmitted, is changed to blood, and
especially if through the wine it receives the faculty of being transmuted into
heat. Since, then, that God-containing flesh partook for its substance and
support of this particular nourishment also, and since the God who was
manifested infused Himself into perishable humanity for this purpose, viz. that
by this communion with Deity mankind might at the same time be deified, for
this end it is that, by dispensation of His grace, He disseminates Himself in
every believer through that flesh, whose substance comes from bread and wine,
blending Himself with the bodies of believers, to secure that, by this union
with the immortal, man, too, may be a sharer in incorruption. He gives these
gifts by virtue of the benediction through which He
transelements the natural quality of these visible things to that immortal
thing. (Gregory of Nyssa, The Great Catechism 37 [NPNF2 5:502-3])
