In "Stopping by Woods on a Snowy Evening," the speaker is tired from the journey of life. He stops by the woods on the darkest evening of the year. Even the little horse thinks it is strange to be stopping by the woods on the darkest evening of the year. Also, we know that the speaker has miles to go. The question is why would he stop with miles to go before he can sleep?
It is a good question. It is as if the speaker does not desire to go on, but because of responsibilities, the speaker knows he must go on. He has promises to keep.
Some would analyze that the speaker is ready for death. He is contemplating suicide. He is tired of living. This could be the truth of the matter. Otherwise, why would the speaker stop to watch woods fill up with snow on the darkest evening of the year with miles to go before he can get home? Also, there is no farmhouse near and a frozen lake rests between the speaker and home. It is quite dangerous to be stopping at dark with miles to go.
The speaker could be referring to miles to go before he sleeps as symbolic for miles to go in life. The speaker could be using symbolism for the miles to go or he could literally have many miles to go before he reaches home.
Either way, the speaker desires to stop and watch the lovely, dark and deep woods fill up with snow. Most likely, this speaker has seen snow before. No doubt, he has witnessed the woods filling up with snow before, but on this occasion, he desires to stop and not go on. This could indicate that the speaker is tired of the journey called life but because of the promises he has made, he must go on.