10 After the sacrament of the miracle, He introduces discourse, that, if possible, they who have been fed may be further fed, that He may with discourse fill their minds, whose bellies He filled with the loaves, provided they take in. And if they do not, let that be taken up which they do not receive, that the fragments may not be lost. Wherefore let Him speak, and let us hear. “Jesus answered and said Verily, verily, I say unto you, you seek me, not because ye saw the signs, but because you have eaten of my loaves.”
You seek me for the sake of the flesh not for the sake of the spirit. How many seek Jesus for no other object but that He may bestow on them a temporal benefit! One has a business on hand, he seeks the intercession of the clergy; another is oppressed by one more powerful than himself, he flies to the church. Another desires intervention in his behalf with one with whom he has little influence. One in this way, one in that, the church is daily filled with such people. Jesus is scarcely sought after for Jesus' sake.
“You seek me, not because you have seen the signs, but because you have eaten of my loaves. Labor not for the meat which perishes, but for that which endures unto eternal life.” You seek me for something else, seek me for my own sake. For He insinuates the truth, that Himself is that meat: this shines out clearly in the sequel. “Which the Son of man will give you.” You expected, I believe, again to eat bread, again to sit down, again to be gorged. But He had said, “Not the meat which perishes, but that which endures unto eternal life,” in the same manner as it was said to that Samaritan woman: “If you knew who it is that asks of you drink, you would perhaps have asked of Him, and He would give you living water.”
When she said, “Whence have you, since you have nothing to draw with, and the well is deep?” He answered the Samaritan woman: “If you knew who it is that asks of you drink, you would have asked of Him, and He would give you water, whereof whoso drinks shall thirst no more; for whoso drinks of this water shall thirst again.” And she was glad and would receive, as if no more to suffer thirst of body, being wearied with the labor of drawing water. And so, during a conversation of this kind, He comes to spiritual drink. Entirely in this manner also here.
Source: Tractates on the Gospel of John (New Advent)