19 But when Moses came down, he saw their heathenism revelling in the wide plain with drums and cymbals. Speedily, he put their madness to shame by means of the Levites and drawn swords. So likewise here, our Lord concealed His knowledge for a little when the sinful woman approached Him, that the Pharisee might form into shape his thought, as his fathers had shaped the pernicious calf. But when the Pharisee's error came to a head within him, then the knowledge of our Lord was manifested against it and dispelled it; I entered into your house; you gave Me no water for My feet: But she has moistened them with her tears.
Therefore her sins which are many are forgiven her. But the Pharisee when he heard our Lord naming the sins of the woman, many sins, was greatly put to shame because he had greatly erred. For he had supposed that our Lord did not even know that she was a sinner. Our Lord had before shown Himself as though not knowing her for a sinner. For He allowed him who had seen His signs, to show the doubt of his mind, that it might become manifest that his mind was bound in the ungodliness of his fathers.
But the physician, who by his medicines brings out the hidden disease, is not the helper of the disease but its destroyer. For while the disease is hidden, it rules in the members, but when it is made manifest by medicines, it is rooted out. So then the Pharisee saw great things and doubted about small things. But when our Lord saw that his littleness made little of great things in his mind, He speedily showed him not only that she was a sinner, but even the multitude of her sins; that he might be put to shame by little things—he who had not believed in wonders.
Source: On Our Lord (New Advent)