11 Accordingly, after saying, “Now shall the prince of this world be cast out,” He added, “And I, if I be lifted up from the earth, will draw all things after me.” And what “all” is that, but those out of which the other is ejected? But He did not say, All men, but “all things;” for all men have not faith. And, therefore, He did not allude to the totality of men, but to the creature in its personal integrity, that is, to spirit, and soul, and body; or all that which makes us the intelligent, living, visible, and palpable beings we are. For He who said, “Not a hair of your head shall perish,” is He who draws all things after Him. Or if by “all things” it is men that are to be understood, we can speak of all things that are foreordained to salvation: of all which He declared, when previously speaking of His sheep, that not one of them would be lost. And of a certainty all classes of men, both of every language and every age, and all grades of rank, and all diversities of talents, and all the professions of lawful and useful arts, and all else that can be named in accordance with the innumerable differences by which men, save in sin alone, are mutually separated, from the highest to the lowest, and from the king to the beggar, “all,” He says, “will I draw after me;” that He may be their head, and they His members. But this will be, He adds, “if I be lifted up from the earth,” that is, when I am lifted up; for He has no doubt of the future accomplishment of that which He came to fulfill. He here alludes to what He said before: “But if the grain of wheat die, it brings forth much fruit.” For what else did He signify by His lifting up, than His suffering on the cross, an explanation which the evangelist himself has not omitted; for he has appended the words, “And this He said signifying what death He should die.”
12. “The people answered Him, We have heard out of the law that Christ abides for ever: and how sayest Thou, The Son of man must be lifted up? And who is this Son of man?” It had stuck to their memory that the Lord was constantly calling Himself the Son of man. For, in the passage before us, He does not say, If the Son of man be lifted up from the earth; but had called Himself so before, in the lesson which was read and expounded yesterday, when those Gentiles were announced who desired to see Him: “The hour has come that the Son of man should be glorified”. Retaining this, therefore, in their minds, and understanding what He now said, “When I am lifted up from the earth,” of the death of the cross, they inquired of Him, and said, “We have heard out of the law that Christ abides for ever; and how sayest Thou, The Son of man must be lifted up? Who is this Son of man?” For if it is Christ, He, they say, abides for ever; and if He abides for ever, how shall He be lifted up from the earth, that is, how shall He die through the suffering of the cross? For they understood Him to have spoken of what they themselves were meditating to do. And so He did not dissipate for them the obscurity of such words by imparting wisdom, but by stimulating their conscience.
13. “Then said Jesus unto them, Yet a little light is in you.” And by this it is you understand that Christ abides for ever. “Walk, then, while you have the light, lest darkness come upon you.” Walk, draw near, come to the full understanding that Christ shall both die and shall live for ever; that He shall shed His blood to redeem us, and ascend on high to carry His redeemed along with Him. But darkness will come upon you, if your belief in Christ's eternity is of such a kind as to refuse to admit in His case the humiliation of death. “And he that walks in darkness knows not whither he goes.” So may he stumble on that stone of stumbling and rock of offense which the Lord Himself became to the blinded Jews: just as to those who believed, the stone which the builders despised was made the head of the corner. Hence, they thought Christ unworthy of their belief; because in their impiety they treated His dying with contempt, they ridiculed the idea of His being slain: and yet it was the very death of the grain of grain that was to lead to its own multiplication, and the lifting up of one who was drawing all things after Him. “While you have the light,” He adds, “believe in the light, that you may be the children of light.” While you have possession of some truth that you have heard, believe in the truth, that you may be born again in the truth.
14. “These things spoke Jesus, and departed, and did hide Himself from them.” Not from those who had begun to believe and to love Him, nor from those who had come to meet Him with branches of palm trees and songs of praise; but from those who saw and hated Him, for they saw Him not, but only stumbled on that stone in their blindness. But when Jesus hid Himself from those who desired to slay Him (as you need from forgetfulness to be often reminded), He had regard to our human weakness, but derogated not in anything from His own authority.
Source: Tractates on the Gospel of John (New Advent)