Jerome : (Verse 16) And I will lead the blind on a path they do not know, and I will make them walk on paths they have not known. I will turn darkness into light in front of them, and I will make crooked paths straight. These are the things I will do for them, and I will not abandon them. LXX: And I will lead the blind along a way they do not know, and I will make their paths uneven; I will turn darkness into light for them, and crooked things into straight paths. I will speak these words to them, and I will not abandon them. And I will lead the blind along a path they did not know, of whom we have also read above: I have made you a covenant of the people, a light of the nations, to open the eyes of the blind. They will be led along the way by which Christ speaks. I am the way, that is, the way of the knowledge of God, and I will make them walk on the prophetical paths. Then their darkness will be changed into light, and their faults will be turned into righteousness, so that they may understand what they read and with the eyes of their hearts may gaze upon the clear light of Christ in the Old Testament. At the same time, he adds: These words that I have spoken or will speak to them do not promise anything further in the future, but fulfill what I promised before. — Commentary on Isaiah Leo the Great : The apostle John teaches how this is fulfilled: "We know that the Son of God came and gave understanding to us, that we might know the truth and be in his true Son." And again, "Let us love, therefore, since God first loved us." By loving us, God restores us to be his image, so that he might find the form of his own goodness in us. He grants that we ourselves might work what he works, indeed setting light to our minds and causing us to burn with the fire of his love, in order that we love not only him but also the things that he loves. — SERMON 12:1 Theodoret of Cyrus : Again, God calls the people who suffer from unbelief and who are devoid of intellectual acuteness "the blind." He promises to guide their steps on the way they do not know, for they failed to recognize the path of the truth but followed on the paths of error. "I will turn darkness into light for them." After freeing them from their previous ignorance, I will deem them worthy of the knowledge of God, for ignorance is like darkness, whereas knowledge is analogous to the light. "And crooked things into straight." For the difficult course of wisdom, of the governing of oneself and of justice, he has made an easy course, since he has attached the hope of future benefits to the efforts to claim virtue. "These are the words that I will fulfill for them; and I will not forsake them." I will not cease to judge them worthy of these benefits, and I will lavish all kinds of care, even to the future. — COMMENTARY ON Isaiah 12:42.16