When the soul loses its fervor…

When the soul betrays itself and loses the blessed and longed-for fervor, let it carefully investigate the reason for losing it. And let it arm itself with all its longing and zeal against whatever caused this. For the former fervor can return only through the same door through which it was lost.
–Saint John Climacus (c. 525-606)

The Word of God…

If the Word of God is living and powerful, and if the Lord does all things whatsoever he wills; if he said, “Let there be light,.” and it happened; if he said, “Let there be a firmament,” and it happened; …if finally the Word of God himself willingly became man and made flesh for himself out of the most pure and undefiled blood of the holy and ever Virgin, why should he not be capable of making bread his Body and wine and water his Blood?… God said, “This is my Body“, and “This is my Blood.”

— Saint John of Damascus (c. 676-750)