Ernest Hemingway's novella The Old Man and the Sea is a parable about the indefeasible will and spirit that is man's.  As Santiago himself reflects,

Man is not made for defeat...man can be destroyed, but not defeated.

Santiago's stoic attitude, much like his baseball hero, Joe DiMaggio, who ignores the pain of the bone spurs in his feet and runs the bases, Santiago ignores the pains of age and accepts without complaint whatever life gives him. It is this power to endure about which Hemingway writes.  For, although Santiago presents a tragic figure, who walks with his mast much like Jesus carrying his cross, he is heroic in his struggle to endure.  After his harpoon for killing the sharks is gone, he tells himself,

"Don't think, old man,....Sail on this course and take it when it comes."

When the sharks feed on the marlin that he has caught, the old man determines that he will fight them: "I'll fight them until I die." And, although he is physically worn out when he returns with only a skeleton, the old man returns to his shack and he falls asleep, "dreaming about the lions"; symbolically, he is not defeated.