Having thus made known to them, that He knew their motive in following Him, He goes on to tell them to labour not, that is to say, not so much, for the food that perisheth as for that which endureth unto eternal life. This food enduring unto eternal life (verse 27) we understand to be the Blessed Eucharist. But before giving our reasons for holding that reference to the Blessed Eucharist begins here, and not merely at verses 48, 51, or 52, it is desirable to indicate the Protestant interpretations of this discourse of our Lord, and prove that they are untenable. Most Protestants deny that there is any reference to the Blessed Eucharist in this chapter; they hold that it refers merely to the reception of Christ through faith; and through faith especially in the atoning efficacy of His passion and death. It is of this faith in His passion that they interpret the words: “Except you eat the flesh of the Son of Man, and drink His blood, you shall not have life in you,” (verse 54). Indeed they are logically constrained either to deny that there is reference here to the sacrament of the Eucharist, or else to abandon their teaching regarding the nature and efficacy of the sacraments. On the one hand, if they admit reference to the Eucharist, they see the difficulty of denying the real and substantial presence of Christ in the sacrament; on the other hand, holding, as they do, that the few sacraments which they retain,(55) are not _causes_ of grace, as the Catholic Church teaches, but merely signs or pledges of grace, and external notes of the Church, they find themselves in direct conflict with our Lord, if His words are to be understood of the sacrament of the Eucharist. For again and again throughout this discourse He attributes salvation and grace to the eating of His flesh and the drinking of His blood, in such a way as to leave no room for doubt that whatever it is He speaks of, whether faith or the sacrament of the Eucharist, it is the cause of grace. See, _e.g._, 27, 52, 55, 57, 59. But besides those who deny that there is any reference to the Blessed Eucharist in this chapter, there is a considerable number of Protestants who take up even a more indefensible position. These admit the reference, but contend that nothing more can be concluded from this or any other part of Scripture than that Christ is _spiritually_ present in the Sacrament. They will not admit that Christ is really and substantially present, much less that the sacrament causes grace. Against the first class we shall show that Christ refers, in this discourse, to the Blessed Eucharist; and against the second, that His words prove that He is really and substantially received in the sacrament. I. CHRIST REFERS IN THIS DISCOURSE TO THE BLESSED EUCHARIST.(56)