13. Now our Lord has not left the minds of His faithful followers in doubt, but has explained the manner in which His nature operates, saying, That they may be one, as We are one: I in them and Thou in Me, that they may be perfected in one Ib. 22, 23.. Now I ask those who bring forward a unity of will between Father and Son, whether Christ is in us to-day through verity of nature or through agreement of will. For if in truth the Word has been made flesh and we in very truth receive the Word made flesh as food from the Lord, are we not bound to believe that He abides in us naturally, Who, born as a man, has assumed the nature of our flesh now inseparable from Himself, and has conjoined the nature of His own flesh to the nature of the eternal Godhead in the sacrament by which His flesh is communicated to us? For so are we all one, because the Father is in Christ and Christ in us. Whosoever then shall deny that the Father is in Christ naturally must first deny that either he is himself in Christ naturally, or Christ in him, because the Father in Christ and Christ in us make us one in Them. Hence, if indeed Christ has taken to Himself the flesh of our body, and that Man Who was born from Mary was indeed Christ, and we indeed receive in a mystery the flesh of His body—(and for this cause we shall be one, because the Father is in Him and He in us),—how can a unity of will be maintained, seeing that the special property of nature received through the sacrament is the sacrament of a perfect unity If in the Sacrament we hold real communion with the Father and the Son, the union of Father and Son on which it is based must be also real, and not a mere concord of will.?