Rom 2:19

“"And art confident that thou thyself." Here again he does not say that thou art "a guide of the blind," but "thou art confident," so thou boastest, he says. So great was the unreasonableness of the Jews. Wherefore he also repeats nearly the very words, which they used in their boastings. See for instance what they say in the Gospels. "Thou wast altogether born in sin, and dost thou teach us?" (John ix. 34.) And all men they utterly looked down upon, to convince them of which, Paul keeps extolling them and lowering the others, that so he may get more hold on them, and make his accusation the weightier. Wherefore he goes on adding the like things, and making more of them by different ways of relating them. For "Thou art confident," he saith, "that thou thyself art a leader of the blind, An instructor of the foolish, a teacher of babes, which hast the form of knowledge and truth, which is in the Law." Here again he says not, in the conscience and in actions and in well-doings, but "in the Law;" and after saying so, he does here also what he did with regard to the Gentiles. For as there he says, "for wherein thou judgest another, thou condemnest thyself," so saith he here also.”

“Above he said that hearing the law brings no benefit if doing it is not joined to it; "for not the hearers of the law," he says, "are righteous before God, but the doers of the law" (v. 13), now he says something greater, namely: even if you were a teacher, but if you do not fulfill the law, then not only do you gain no benefit for yourself, but you also bring upon yourself a greater punishment. And since the Jews greatly boasted of their dignity as teachers, from this especially he proves that they are worthy of ridicule. For when he says: "a guide of the blind, a teacher of babes," and the rest, he depicts the arrogance of the Jews, who called themselves guides, a light, and instructors, while those converted from paganism they called those in darkness, babes, and ignorant.”

“Then he mentions its fruit with respect to others who find themselves in three different situations, so far as knowledge of the law is concerned. For some are entirely ignorant of the law, because they lack natural talent, just as a man is physically blind, because he lacks visual power: we grope for the wall like the blind (Isa 59:10). To such persons cannot be given the light of knowledge enabling them to see by themselves what to do; rather, they must be led, as the blind are, by commanding them to do this or that, even though they do not understand the reason for the command: I became an eye to the blind (Job 29:15); they are blind and leaders of the blind (Matt 15:14). Others are ignorant through lack of training, being as it were in the exterior darkness and not enlightened by teaching. To such persons a wise man can offer the light of training, so that they will understand what is commanded. This is why he says, a light of those who are in darkness: to give light to those who sit in darkness and the shadow of death (Luke 1:79).”