"A Piece of Steak" teaches readers several things about wisdom: first, that it only comes with age, and second, that it only comes when we are unable to take full advantage of it—for Tom King, this manifests at the beginning of the story as regret. We meet Tom as a forty-year-old, broken-down prize-fighter whose body and strength are betraying him:

He had never heard that a man's life was the life of his arteries, but well he knew the meaning of those big, upstanding veins . . . No longer could he do a fast twenty rounds, hammer and tongs, fight, fight, fight . . . .

His youth spent fighting had wreaked havoc on him physically, and he was no longer as powerful as he had been.

He found himself wishing that he had learned a trade. It would have been better in the long run,

London writes—but when Tom was young, it was easy money, and he was a celebrity in the fighting world. Everything came easy to him. At forty, however, nothing came easy anymore—he wasn't winning fights, he and his family were starving, and they had not a penny to their names, all because he relied a little too heavily on his fighting—on his physical vitality—as a young man, instead of taking up a trade that could support him throughout his life. And now that he has the wisdom to look back and see where he went wrong, it's too late.

During the main action of the story, London compares the recklessness of youth with the patience and understanding of old age, as Tom King dukes it out with the young upstart Sandel, who

wanted to make the pace fast, while King, out of his wisdom, refused to accommodate him.

King understands the folly of quick, poorly-aimed punches, because he has been there himself—his age and experience contribute to the wisdom of strategy, "bred of long, aching fights." And for awhile we think that King might actually win the fight, that his dogged, slow, calculating method might actually work. But Sandel refuses to stay down, and in the end, the quickness and resilience of youth ends up putting King away.

For King,

his body had deserted him. All that was left of him was a fighting intelligence that was dimmed and clouded from exhaustion.

And here London exhibits the great irony of wisdom: that once you are in possession of it, once you have the experience to understand the follies of youthful attitudes, you are in no shape to exercise it to any positive end. In the same way, King says,

Sandel would never become a world champion. He lacked the wisdom, and the only way for him to get it was to buy it with Youth; and when wisdom was his, Youth would have been spent in buying it.

By the end of the story, King understands what made the "old 'uns" cry after losing fights at the end of their careers: the confidence and health of their youth had abandoned them, leaving them with nothing but an empty stomach, a poverty-stricken family, and no skills. But this wisdom, being able to understand the plight of the old, comes too late.