Frost was eager to show that his excellence extended also to the shortest of figures, as in the perfectly limpid, toneless assertion of "Nothing Gold Can Stay". . . .
The elegant "subsides" gently names the process of natural changing and metaphorical couplings within the poem; as "green is gold," as "Her early leaf’s a flower" (where the contraction makes even more imperceptible the seeing of one thing in terms of another), as "dawn" changes both in fact and in words (from "dawn" to "day"). The poem is striking for the way it combines the easy delicacy of "Her early leaf’s a flower" with monumentalities about Eden and the transient fading of all such golden things, all stated in a manner that feels inevitable. It is as if in writing "Nothing Gold Can Stay," Frost had in mind his later definition of poetry as a momentary stay against confusion. The poem's last word proclaims the momentariness of the "gold" that things like flowers and Eden, dawn and poems share. So the shortness of the poem is also expressive of its sense.
From Frost: A Literary Life Reconsidered. Copyright © 1984 by William Pritchard.