Frost's poem is profound in how it shows existence as something that is mutable. The only permanent element in consciousness is that there is change. There is something profound in this. Frost is able to offer a glimpse into this condition of being through a few lines that stick in the mind's eye. For example, "Her hardest hue to hold" in reference to the opening image of "Nature's first green is to gold." The idea that beauty, the morning pristine vision, is something that is "hardest to hold" even for the natural world is quite profound. Frost seeks to bring out in the opening two lines that even nature cannot hold on to that which seems perfectly beautiful. The most tender and wonderful moments in our being are transitory ones. The happiness we experience in these instances are "the hardest hue to hold." We are compelled to see that what nature has to endure, we do too. Frost's poem does not make the reader entirely sad about being in the world, but rather forces one to accept that we must treasure our happiness, and not take it for granted as it can leave as easy as it arrives.
The subsequent images do much to bring this picture of being into focus. "Eden" sinking to "grief" is another such image that forces the reader to understand the transitory nature in being in the world. The idyllic garden is one that is in passing. Even the creation of the divine, the realm where all is good and right, sinks according to the weight of time. Frost's poem is a reminder that our lives are lived from the hopeful joyful experience of one instant that passes to another lying in wait. We swing from vine to vine of happiness moment to another moment of joy. The idea that "nothing gold can stay" reminds us of just as the condition of nature and the creation of the divine, we, too, are bound to only enjoy what we can when we can. It is not permanent. Our happiness is elusive as it passes our grasp and Frost's poem is a reminder to revel in it because "nothing gold can stay."