Impermanence
The central theme of this poem is impermanence. While real gold itself may be able to withstand the test of time, nothing to which the speaker compares gold—beauty, youth, goodness—can last forever, or even for very long. The speaker's problem with dawn turning to day seems more to do with losing spring than it does with disliking day; every beautiful thing ends, and ends in sorrow. When "Eden sank to grief," the Garden literally vanished, or at least receded from the reach of humans. Even the poem itself is brief, and the last line ends a syllable shorter than the rest, gesturing toward the premise.
Beauty, Youth, and Goodness
This poem does not straightforwardly refer to beauty, youth, and goodness, but their presence is implied by the mentions of the young leaves, dawn, and the green of early spring. However, youthfulness may not be the only thing represented by these images; vitality and health, as well as happiness, feel implied. The imagery that Frost uses to represent youth and beauty—blooming nature and dawn—are quite standard, but the imagery used to envision endings—daytime and leaves subsuming leaves—are less so; summer leaves and daytime are more often used to signify vitality, while in this poem, they signify precisely its opposite. This shows the reader that the speaker's antagonist is time: anything that involves time's passage reveals future decay, even if the decay is not yet evident.
Nature
Nature plays an important role in this poem. Frost's choice to use nature imagery and not to include a single human figure would suggest that the speaker is not talking about mankind. However, the mention of the Garden of Eden and the speaker's obvious yet muted grief suggest that the references to nature in this poem, such as the blooming leaves and flowers, are partly metaphors for the human lifespan, or at least for the things we consider good. Nature, however, is not a perfect metaphor for the transience of beauty and goodness; spring comes back year after year, but this is not a source of comfort for the speaker. Though beauty itself may always return, and though the saved members of the human race, according to Christianity, will return to paradise, the loss of each leaf is tragic for the speaker. This shows the specificity of the speaker's longing and reveals that, while the speaker may seem removed from the poem, the immortality of the concepts of beauty and goodness is not important to him; the losses he grieves are personal.
