Shakespeare's Sonnet 73 embodies the excessiveness of poetry. It’s possible to summarize the poem in a brief statement: “I’m getting old. I'll die. Love me while you can.” Why so belabor the point?

One effect of belaboring through fourteen lines of iambic pentameter is to link aging with cosmic cycles and natural elements. The first quatrain operates mostly within the framework of seasonal change. The addressee can behold a “time of year” in him, the time of year when leaves are no longer green but jaundiced, yellow. The strange sequence of “leaves . . . none . . . few” suggests that he is in fact “hanging,” as the word “hang” hangs at the end of line 2: He is not quote stripped of leaves, but almost. Only a few remain.

He is the tree, leaves now in sere, his bare branches shaking in the cold autumn wind. Those shaking branches are also his arms and legs; like David in his dotage, he can’t keep himself warm at night, no matter how many blankets he piles up.

The fourth line shifts the context. The tree is now a cathedral, the branches the choir, the songbirds silenced singers who have departed to escape the approaching winter. Critics are right to hear a lament for the ruin’d choirs of Protestant England, the monasteries stripped of their songbirds. If the speaker is a tree losing his leaves, he is also an empty, silent cathedral church.

This is how Shakespeare's poetic imagination works: A man is like a tree is like a cathedral; arms are like branches are like a church choir; old age is like autumn is like an empty church.

The second quatrain tightens the temporal frame, moving from the annual to the daily round of time. As he is autumnal, so he is in the twilight of his day. The sun has already faded west, though darkness has not yet completely overcome him. That tightening intensifies the feeling of impending loss. The speaker's end is no longer a season away, but a few hours. Black night is “death’s second self,” the death of each day’s life, the daily rest after the bustle of the day that anticipates the final rest of death.

The third quatrain reaches for another image, not a temporal but an elemental one. The aging speaker is like the smoldering embers of a once-raging fire. There’s still some little light and warmth to be hand, but not much. The fire image is filled out complexly in lines 10–12. The ashes in which the final embers glow are the ashes of youth; youth has been consumed in the fire. Strikingly, youth, not age, is the deathbed of the fire of life or the soul. Perhaps more directly, youth’s ashes form the deathbed for youth itself. Youth is consumed with the very thing that nourished it. The energy, hope, fire of youth is the very thing that burns youth out, and leaves it a glowing heap of embers, barely alive.

The concluding couplet states a truism: The speaker is in the autumn of life, a twilight man, a dying fire, the addressee’s love should become stronger. Love well what someday you will not be able to love at all love at all. From the opening lines of the poem, we knew that sentiment was coming, but the path, rather than the destination, is the point. And if the destination illustrates the excess of poetry, the path exemplifies poetry’s almost infinite capacity of concentration.