"The Ball Poem" is arguably about the process of dealing with death for the first time. The ball in the poem symbolizes a life that is lost. When the ball is lost, in the water of the harbor, the boy "stands rigid, trembling," and is clearly in shock. It is no use thinking, "O there are other balls," because the ball that he has lost, like a life that might be lost, was unique and irreplaceable. As the boy looks into the water, contemplating death and loss, he imagines that not only the ball, but also "All his young days" have been lost in the water. The implication here is that when one first experiences the death of a loved one, it can feel as if all of one's carefree days have also been lost forever. One's life is now irreversibly marked with death.

Toward the end of the poem the speaker remarks that, "gradually light returns to the street." The gradual return of the light alludes to the fact that after the initial shock of one's first experience of death, life does gradually return to something like normal. The speaker then says that soon a part of him "will explore the deep and dark / Floor of the harbour." This suggests that the speaker is close to death himself, and so the floor of the harbor is, here, a metaphor for death. He continues to suggest that his body is failing, and taking him toward the water, and "under the water." The final line, "I am not a little boy," suggests that he is in fact the opposite. He is an old man, not much longer for this life.

"The Ball Poem" by John Berryman is talking about the irreversability of loss and the need to accept loss and move beyond it as one matures. Some actions simply cannot be taken back, no matter how much one wants to. For this particular boy, the loss of the ball has marked a realization that has brought part of his youth to a close:

....he stands rigid, trembling, staring down
All his young days into the harbour where
His ball went.

The boy realizes that the ball was lost because of his actions:

.....Now
He senses first responsibility
In a world of possessions.

He is learning what loss truly means (the "epistemology of loss" -- epistemology being the study of how we know things), and that it is necessary to go on after loss, to "stand up." Eventually, he may mature into the more complex reality of the narrator of the poem, who has gone beyond acceptance of loss to an attempt to comprehend it,

....I am everywhere,
I suffer and move, my mind and my heart move
With all that move me...