In Robert Frost's poem, each line is eight syllables long and each stanza is organized into an aaba rhyme scheme. I believe this flow of the poem strengthens the image of rhythmically falling snow. Also, the fact that the poem is not awkwardly broken up and does not make the reader uncomfortable with any unexpected deviation from the expected pattern relates to the calm and consistency of nature as presented in the poem.
As the man in the poem pauses in the woods before travelling on, the moment is described as a temporary escape and relief from reality. Although he has promises to keep and miles to go, he pauses in a scene of natural tranquility and peacefulness away from all of his worldly demands. The moment almost seems stolen and coveted by the man. He knows he is trespassing on another man's land and that he has expectations and goals to meet, yet he cannot help but stop and become entranced by the mystical woods.
The woods are given mysterious and dreamlike qualities in the poem. It is the darkest night of the year and there are no sounds other than the wind and the soft sound of snowfall. Measures of time seem to be distorted when Frost contrasts the fleeting moment of stopping in the woods with the lengthy image of watching the woods fill up with snow. The man seems to be stopping only for a moment before deciding to move on but at the same time seems to be in stasis there for a long time.
In the end, the man resists the draw of dissappearing from his responsibilities into the woods. The last line "And miles to go before I sleep" is repeated twice. This emphasizes his lackluster acceptance of needing to continue on in life. It seems as though he must repeat the thought to himself in order to finally be convinced to move on.