The simplest way to express what Christ asks us to believe about the Real Presence is that the Eucharist is really He. The Real Presence is the real Jesus. We are to believe that the Eucharist began in the womb of the Virgin Mary; that the flesh which the Son of God received from His Mother at the Incarnation is the same flesh into which He changed bread at the Last Supper; that the blood He received from His Mother is the same blood into which He changed wine at the Last Supper. Had she not given Him His flesh and blood there could not be a Eucharist.
We are to believe that the Eucharist is Jesus Christ - simply, without qualification. It is God become man in the fullness of His divine nature, in the fullness of His human nature, in the fullness of His body and soul, in the fullness of everything that makes Jesus Jesus.
He is in the Eucharist with His human mind and will united with the Divinity, with His hands and feet, His face and features, with His eyes and lips and ears and nostrils, with His affections and emotions and, with emphasis, with His living, pulsating, physical Sacred Heart.
That is what our Catholic Faith demands of us that we believe. If we believe this, we are Catholic. If we do not, we are not, no matter what people may think we are.Father John A. Hardon S.J.