Except the smaller size

Except the smaller size
No lives are round —
These — hurry to a sphere
And show and end —
The larger — slower grow
And later hang —
The Summers of Hesperides
Are long.
                          F606 (1863)  J1067

While it is easy, Dickinson implies in this short poem, for "smaller" lives to reach a satisfying completion before they pass on, "larger" souls have a longer process. Dickinson refers to the fabled Garden of the Hesperides (the Daughters of the Night) whose golden apples confer immortality.
        The first half of the poem depicts the exception to Dickinson's claim that "No lives are round". In contrast to the large Hesperian apples she invokes at the end, we can imagine little crab apples – among apples the smallest, roundest, and among the first to ripen. Some people likewise peak early. They have their day while the rest of us are flailing about, but their "show" is soon over. There are also those content with simple lives within the strictures of their times. Never deforming or chafing into rough edges, they too ripen quickly.

Garden of the Hesperides
Frederick Leighton, 1891

        Most people, however, struggle to establish themselves, exploring the myriad paths they find before them and often becoming battered in the process. But it is not these whom Dickinson emphasizes in this poem. When she invokes the Hesperides, she invokes the few who ripen slowly into some real greatness and immortality.
        It's helpful here to look at the history of this poem. It was first sent to Susan Dickinson, perhaps accompanied by apples [Emily Dickinson's Vision: Illness and Identity in Her Poetry, James Robert Guthrie, p. 88]. Later, in early 1866, she included it in a poem to Thomas Wentworth Higginson (L316):

"I will be patient – constant, never reject your knife and should my slowness goad you, you knew before myself that
Except the smaller size … ".

Ah… among those lives slowly growing golden and pendulous within the sacred orchard are poets, one of whom is Dickinson herself. And might some of those smaller apples be lesser poets? If so, Dickinson was taking a true measure of her worth. Her poetry endures and the appreciation of it continues to widen while poets regularly published in her day have by and large dropped from the tree. (Dickinson claims to have never read Whitman – oh, if only she had and detailed her response in one of her famous letters!)

The poem's pace mirrors the images. The smaller apples are dispatched with the quick-reading "hurry to a sphere" after which the poem moves with an almost heavy grandeur achieved by long vowels and dipthongs: show, larger, slower grow, and later.

The two-syllable last line, "Are long", hangs in its open space like the slowly ripening apples.