Secondly, the Trinity of the Divine Persons; for the sacrifice consists in the offering of God the Son in His human nature as a sin-offering for man to His Father: "Wherein the same Christ is contained, and immolated without blood, who once on the altar of the cross offered Himself with blood;"[101] which, moreover, is accomplished by the descent of the Holy Ghost upon the gifts. Thus the three Divine Persons enter into the sacrifice, He to whom it is offered, He who offers it, and He by whose operation it is consummated. So distinct yet so interwoven is their action, so divine in each, that the sacrifice guards the doctrine of the most Blessed Trinity as it guards that of the Divine Unity, and those who offer this sacrifice are faithful in the maintenance of the second mystery as in that of the first. But the Divine Unity and Trinity is the very life of God, the very source of beatitude, to the knowledge and the faith of which this sacrifice subserves. It preaches these truths as no mere word could preach them; for action and word enter into each other and complete themselves reciprocally in the sacrifice. Thirdly, the stupendous mystery of God the Creator assuming a created nature for the sake of the creature enters into the very substance of the sacrifice. This can scarcely be expressed more distinctly than by the very words of St. Justin Martyr in the second century, who says, "We receive not these as common bread or common drink, but as by the word of God Jesus Christ our Saviour, having been made flesh, had both flesh and blood for our salvation, so we have been taught also that the food which has been blessed by the word of prayer made by Him, from which our blood and our flesh are by their change nourished, are the flesh and the blood of that incarnate Jesus. For the Apostles, in their memorials called the Gospels, have handed down that thus Jesus enjoined them: that He took bread, and having blessed it, said, This do in commemoration of Me: this is My Body; and that He took likewise the chalice, and having blessed it, said, This is my Blood."[102] Here the martyr appeals to the reality of the flesh assumed by the Word, as a supposition necessary to understand the reality of His Body and Blood in the Eucharist, as St. Ignatius had done before him, and as St. Irenæus and others did after him.[103] In this connection, Eusebius of Cæsarea, setting forth the typical character of the Jewish Pasch and its fulfilment in the new covenant, says, "The followers of Moses sacrificed the Paschal Lamb only once a year, on the fourteenth day of the first month about evening tide, but we in the new covenant celebrating the Pasch every Sunday, are ever satisfied with the Body of the Lord, and ever take part in the Blood of the Lamb."[104] And here, once more, wherever this sacrifice is truly offered, the offerers show themselves truly penetrated by that belief which comes next in preciousness and dignity to the belief in the Divine Unity and