What's Hemingway saying?

Hemmingway is speaking of the nature of the sea and the fish that live there. He sees their noble bearing, their strength, and their survival. Only man's intelligence can thwart them, and man is not so noble about the death he seeks. We do not stop our abuse of nature simply to fulfill our needs.... we rather satiate our desires. The marlin takes what it needs from nature, enough to survive.