At His command...

"And so, Father, we bring you these gifts. We ask you to make them holy by the power of your Spirit, that they may become the body and blood of your Son, our Lord Jesus Christ, at whose command we celebrate this Eucharist." -- Liturgy of the Eucharist

"A wife does not have authority over her own body, but rather her husband, and similarly a husband does not have authority over his own body, but rather his wife" --1 Corinthians 7:4

St. Paul writes that husband and wife no longer have authority over their own bodies but rather each others. They are to love and serve each other as themselves and be in perfect obedience to each other. Out of this obedience and trust can perfect love grow and blossom. This is true also in our union in one flesh with Christ in the Eucharist. It is at His command that we celebrate the Eucharist, that we, His bride the Church, are united with Him in one flesh-- yet by becoming the bread and wine He has given us complete control of His own body as well. Thus in the Eucharist we have the most perfect of obedience, trust and surrender of Love.