I can push this comparison even further. Think about a hunter who tracks wild animals back to their caves. He values setting traps to catch wandering beasts and making his hounds surround the forest so he can follow their tracks. But doing this means he ignores far more important things and leaves many duties undone. The same thing happens to someone who chases pleasure. He puts everything else second to it. He ignores the most important thing of all — his freedom — and trades it away to satisfy his appetites. He doesn't buy pleasure for himself. He sells himself to pleasure.
I may even press this analogy further: as the man who tracks wild animals to their lairs, and who sets great store on—
"Seeking with snares the wandering brutes to noose,"
and
"Making their hounds the spacious glade surround,"
that he may follow their tracks, neglects far more desirable things, and leaves many duties unfulfilled, so he who pursues pleasure postpones everything to it, disregards that first essential, liberty, and sacrifices it to his belly; nor does he buy pleasure for himself, but sells himself to pleasure.