Proverbs 27:19 - Joseph Benson’s Commentary on the Old and New Testaments

As in water face answereth to face As the image of a man's face in the water answers to his natural face who looks into it; or, as in water one man's face is like another's, the difference of men's faces being not there visible; so one man resembles another not only in the regard of the corruption of nature, which is alike in all men, but also with respect to the tempers and dispositions of their minds, wherein likewise they frequently agree. Dr. Grey thinks the verse should be rendered, “As the water showeth the face to the face, so doth the heart the man to the man.” In which sense Castalio seems to have understood it, paraphrasing it thus: “As a man may know what kind of a face he hath if he will look into the water, so he may know what kind of a man he is if he will examine his conscience.” Another interpretation, adopted by some, is, “A man may see himself, while he looks upon other men, as well as know other men, by considering himself, and that as certainly as he can see his own face in the water, or in any other mirror;” there being little or no difference between one man and another by nature, but the difference being made by the grace of God.