Of apple-picking: I am overtired Of the great harvest I myself desired. There were ten thousand thousand fruit to touch, Cherish in hand, lift down, and not let fall. For all That struck the earth, No matter if not bruised or spiked with stubble, Went surely to the cider-apple heap As of no worth.
The narrator has been picking apples for so long that he is not only tired of it, but beginning to question the system. He wonders why all apples that fall, no matter what happens to them, become worthless. This wisdom can be related to some things other than apple picking.
It's also interesting that the narrator begins to notice the flaws in the system after so much time. It seems like time should make him numb to the flaws, not the opposite.