Another theme of "Birches" is the interrelationship between imagination and reality.
In one of Frost's poems, "Tree At My Window," the speaker talks to a tree, telling it that he has seen it "taken and tossed," much as he has been when he sleeps,
You have seen me when I was taken and swept
And all but lost....
Your head so much concerned with outer,
Mine with inner, weather.
So, too, does the boy's/man's reality mirror the movement of the birches in Frost's "Birches." Just as in the other poem, the speaker draws parallels between the tree and himself: He likes to think of the bent birches as having been swung upon by a boy who subdued them just as he did when
[H]e learned all there was
To learn about not launching out too soon
And so not carrying the tree away
Clear to the ground. He always kept his poise
To the top branches, climbing carefully....
Then he flung outward, feet first, with a swish,....
And then the speaker reflects that like the boy, he, too, was
...once myself a swinger of birches,
And so I dream of going back to be.
This "swinger of birches" is a metaphor for the person of imagination and youthful spirit. The speaker may have become sidetracked by obligations and the tedium of daily life, yet he longs for the flights of fancy that he once enjoyed as a boy, the carefree swinging on the branches of the birches in which his imagination delighted and his spirit was free, not "weary of considerations" for his mundane existence.
"One could do worse than be a swinger of birches." That is, one who can move back and forth between reality and imagination is, perhaps, the most content with his life because the carefree joy balances with the "considerations" that must be attended to in his daily life.
Like much of Frost’s poetry, “Birches” takes a look at the interaction between nature and man. In this case, we have a grown man, the narrator, telling the reader that he recalls what it was like to swing on birch trees when he was young. As an adult, he knows that birch trees are bowed because of the ice that bent their trunks in the winter, but he prefers to think that, like he did as a youngster,
some boy’s been swinging them.
The memory of birch swinging is a release from the cares and trials of adult life, a sort of freedom that takes him back in time. Notice that when Frost describes the problems associated with adult life, he continues to use natural imagery:
It's when I'm weary of considerations,
And life is too much like a pathless wood
Where your face burns and tickles with the cobwebs
Broken across it, and one eye is weeping
From a twig's having lashed across it open.
Thus, as we grow, play and adventure is replaced with pain, danger, and weariness.
Frost concludes with something of an understatement in the poem’s final line:
One could do worse than be a swinger of birches.
This emphasizes Frost’s point that interacting with nature in a playful way is actually more rewarding than the responsibilities that accompany adult life.
In good writing there are usually numerous possible themes. It depends on how the reader perceives the work. In “Birches” we might say that the theme is something like “the memory of the joy of youth is a relief from the cares of adult life.” Or, if one preferred to work the idea of nature into a theme, we might say, “The interaction of man and nature imbues our lives with more meaning that the expectations of society.”
"Birches" by Robert Frost is more than a nostalgic picture of boyhood play. From line 43 on, the poem develops a flamboyant metaphor. The poem’s theme can be: “While there are times when the speaker [of “Birches”] would ‘like to get away from earth awhile,’ his aspiration for escape to something ‘larger’ is safely controlled by the recognition that birch trees will only bear so much climbing before returning you, under the pressure of human weight, back home.”
One line in “Birches,” stands out more than the rest, the line about feeling lost in the woods, facing too many decisions about which way to go. He pointed it out to audiences on several occasions: “It’s when I’m weary of considerations” (line 43).
The birch tree can be seen as a path toward heaven fraught with risk, suspense, even a kind of terror. The climbing boy performs his act of birch-bending gracefully, but in doing so goes almost too far, like one filling a cup “even above the brim.”