Genesis 26:15

There are, then, wells which the servants of Abraham dug, but these the Philistines had filled with earth. These, therefore, Isaac first sets about to cleanse. The Philistines hate waters, they love earth; Isaac loves waters, he always seeks wells, he cleanses the old, he opens the new. Behold our Isaac, who "was offered as a victim for us," coming into the valley of Gerar, which is interpreted as "a wall" or "a hedge"—coming, I say, that he might "break down the middle wall of the hedge, the enmities in his flesh"—coming to take away the wall, that is, sin, which separates between us and God, the wall which stands between us and the heavenly powers, that he might make "both one" and carry back the sheep that had strayed "upon his shoulders" to the mountains and restore it to the other "ninety-nine that had not strayed." This Isaac, then, our Savior, when he had come into that valley of Gerar, wills first of all to dig those wells which the servants of his father had dug; that is, he wills to renew the wells of the law and the prophets, which the Philistines had filled with earth. Who are these who fill the wells with earth? Those, without doubt, who place an earthly and carnal understanding in the law and shut up the spiritual and mystical, so that neither do they themselves drink nor permit others to drink. Hear our Isaac, the Lord Jesus, saying in the Gospels: "Woe to you, Scribes and Pharisees, because you have taken away the key of knowledge, and neither did you enter yourselves nor did you permit those who wished." These, then, are they who filled with earth the wells "which the servants of Abraham had dug," who teach the law carnally and defile the waters of the Holy Spirit; who have wells for this purpose, not that they may bring forth water, but that they may put earth in. These wells, then, Isaac sets about to dig. And let us see how he digs them. When Isaac's servants, who are the Apostles of our Lord, were passing, it says, through the grainfields on the sabbath, "they plucked the ears and, rubbing them with their hands, ate them." Then these men, who had filled with earth his father's wells, said to him: "Behold, your disciples do on the sabbath what is not lawful." He, that he might dig their earthly understanding, says to them: "Have you not read what David did, when he himself was hungry and those who were with him—how he entered to Abiathar…