Nothing in Frost more beautifully exemplifies the degree to which "tone of meaning" or sounds of voice create resemblances between birds and Eve, between our first parents and us, between the unfallen and the fallen world. On such resemblances as these Frost would have us imagine a habitable world and a human history. This is a poem which establishes differentiations only that it may then blur them. The delicate hint of a possible but very light sarcasm in the first line blends into but is not wholly dissipated by a concessive "admittedly" in the sixth line. This is one man allowing for another's pride of love but unable to resist the suggestion that perhaps his friend is a bit overindulgent. And the other concessive phrasings, "Be that as may be" and "Moreover," are equally delicate in their effectiveness. For one thing, they tend to take the sting out of the possibly ironic statement that the eloquence of Eve "could only have had an influence on birds"; for another, they lighten the force of "persisted"; and they allow for an almost unnoticeable transition by which the reader is moved from the "garden round" of the second line to "the woods" in line 11.
The tone of the poem is of a speaker who is now here with us and of our time and destiny, while it is at the same time full of a nice camaraderie with our first parents. It is loving and responsible all at once, accepting the parentage of Adam and Eve and the necessary consequences of the Fall, along with the acknowledgment of the possibly good fortunes that also attended it. Eve did come--from Adam and with Adam--in order that the song of birds should, by being changed, mean more than it otherwise would have. The force of the word "aloft" is ever so discreetly crucial here. Her eloquence had power not indiscriminately but only when it was carried to a "loftiness" that belongs to great love and great poetry, neither of which need be separated from the delights of "call or laughter." The "voice upon their voices crossed" became part of Emerson's fossil poetry, awaiting discovery by future readers, and lovers. The ability to hear the "daylong" voice of Eve in bird song teaches us that our own voices, like the voice in this poem, still carry something of our first parents and their difficult history. Mythological identification in this poem consists of voices finding a way to acknowledge and also to transcend historical differences and historical catastrophes. The birds' oversound in relation to words resembles the "sentence sounds" described in the letter, already quoted, which Frost wrote in February 1914 to John Bartlett: "A sentence is a sound in itself on which other sounds called words may be strung." And a bit later he insists that "the ear is the only true writer and the only true reader . . . remember that the sentence sound often says more than the words" (Thompson, Letters, pp. 111, 113).
From Robert Frost: The Work of Knowing. Copyright © 1977 by Oxford University Press.