12.I am the light of the world. Those who leave out the former narrative, which relates to the adulteress, (213) connect this discourse of Christ with the sermon which he delivered on the last day of the assembly. It is a beautiful commendation of Christ, when he is called the light of the world; for, since we are all blind by nature, a remedy is offered, by which we may be freed and rescued from darkness and made partakers of the truelight Nor is it only to one person or to another that this benefit is offered, for Christ declares that he is the light of the whole world; for by this universal statement he intended to remove the distinction, not only between Jews and Gentiles, but between the learned and ignorant, between persons of distinction and the common people.
But we must first ascertain what necessity there is for seeking this light; for men will never present themselves to Christ to be illuminated, until they have known both that this world is darkness, and that they themselves are altogether blind. Let us therefore know that, when the manner of obtaining this light is pointed out to us in Christ, we are all condemned for blindness, and everything else which we consider to be light is compared to darkness, and to a very dark night. For Christ does not speak of it as what belongs to him in common with others, but claims it as being peculiarly his own. Hence it follows, that out of Christ there is not even a spark of true light There may be some appearance of brightness, but it resembles lightning, which only dazzles the eyes. It must also be observed, that the power and office of illuminating is not confined to the personal presence of Christ; for though he is far removed from us with respect to his body, yet he daily sheds his light upon us, by the doctrine of the Gospel, and by the secret power of his Spirit. Yet we have not a full definition of this light, unless we learn that we are illuminated by the Gospel and by the Spirit of Christ, that we may know that the fountain of all knowledge and wisdom is hidden in him.
He who followeth me. To the doctrine he adds an exhortation, which he immediately afterwards confirms by a promise. For when we learn that all who allow themselves to be governed by Christ are out of danger of going astray, we ought to be excited to follow him, and, indeed, by stretching out his hand — as it were — he draws us to him. We ought also to be powerfully affected by so large and magnificent a promise, that they who shall direct their eyes to Christ are certain that, even in the midst of darkness, they will be preserved from going astray; and that not only for a short period, but until they have finished their course. For that is the meaning of the words used in the future tense, he shall not walk in darkness, but shall have the light of life Such is also the import of this latter clause, in which the perpetuity of life is stated in express terms. We ought not to fear, therefore, lest it leave us in the middle of the journey, for it conducts us even to life The genitive of life, in accordance with the Hebrew idiom, is employed, instead of the adjective, to denote the effect; as if he had said, the life-giving light We need not wonder that such gross darkness of errors and superstitions prevails in the world, in which there are so few that have their eyes fixed on Christ.