Besides the Autumn poets sing
A few prosaic days
A little this side of the snow
And that side of the Haze -
A few incisive mornings -
A few Ascetic eves -
Gone - Mr Bryant's "Golden Rod" -
And Mr Thomson's "sheaves."
Still, is the bustle in the brook -
An inconspicuous line which has the power to add a new layer of meaning to the poem. Up to this point the poem seems merely to be describing the onset of autumn (albeit in a very pointed, lyrical manner), but a “A few Ascetic eves -”, following the casual phrasing of its  previous line,  throws the subject into a new light. 
 Asceticism, from the Greek ἄσκησις, “áskēsis”, meaning “training”, is a state of being which shuns worldly pleasures for other-worldly ones, i.e., spiritual growth. Its practice is common among many religions, from the  Abrahamic ones  to Hinduism and Buddhism. 
 
 Hindu ascetics ask Rama for protection 
 Dickinson’s own tendency towards something resembling asceticism is well documented, but the connection isn’t quite that simple– the word is buried under such conversational diction that its power is released slowly over the next few lines. Hers is an asceticism of creation.
Besides the Autumn poets sing 131