Memory is a dominant theme in The Old Man and the Sea. Because of his age, the old man can recall a strength and prowess of his youth. We at first wonder if such elements have faded from his character over time, but are left with a suspicion that the old man in his strength and abilities has lived up to heroic image we see portrayed in his memories of his younger self. We also see that memory is overlaid with current action, that the past can be used to comment on the present (compare the old man’s struggle with the black man in Casablanca to his battle with the fish). The old man’s memory of the lions is a constant motif, as he implicitly compares his own abilities to their prowess and pride.
The old man’s man memories are harmful to him, a painful reminder of the strength, prowess, and respect he no longer has.
The old man’s memories are beneficial for him, encouraging him to fight against the marlin beyond all reasonable measures in order to regain what he once had.