Catholics believe that Jesus is truly present in the Eucharist, under the appearance of bread and wine.  It is not simply a symbol that merely points to Jesus.  We believe that the substance of the bread completely and totally ceases to exist, and that the substance of Christ’s own Body replaces the substance of the bread.  We believe that the wine entirely ceases to exist as wine, and the substance of Christ’s own Blood replaces the wine.  This transformation of the bread and wine into Jesus’ body and blood is called Transubstantiation which happens during the Consecration at Mass.  The Holy Eucharist still looks like bread and wine but it is no longer bread and wine, it is Jesus.  This is a miracle.  This miracle happens by the power of the Holy Spirit through the ministry of the priest’s or bishop’s action in the person of Christ.