It is not the being seen of men that is wrong, but doing these things for the purpose of being seen of men. The problem with the hypocrite is his motivation. He does not want to be holy; he only wants to seem to be holy. He is more concerned with his reputation for righteousness than about actually becoming righteous. The approbation of men matters more to him than the approval of God.
Saint AugustineOur Lord reserved to Himself certain things which He would do in due time in a manner outside the course and order of nature, so that they would wonder and be astonished at seeing not great but unusual things, who are unmoved by things daily seen. For the government of the world is a greater miracle than feeding five thousand men from five loaves; yet at the former no one wonders, the latter astonishes all men: not as a greater wonder, but as a rarer.
Saint AugustineHe who made thee is made in thee. He is made in thee through whom you were made.... Give milk, O mother, to him who is our food; give milk to the bread that comes down from heaven.
Saint Augustine