Besides the beauty of the woods on a snowy evening, what elese holds the poet spellbound in "Stopping by Woods on Snowy Evening"?
The poet stops, not only to appreciate the beauty of the snowfall, but to contemplate life, responsibility, duty and death. It is unusual for a man to stop in a section of the woods that is remote to observe the beauty of nature, but on this particular night, the poet is thinking about the futility of life.
All this work the I have to do, "miles to go before I sleep," (Frost) wouldn't it be lovely to just lie down in this deep dark woods and rest. The poet is thinking about death, about how difficult life is, he is tempted by the serenity that the dark woods represents, the snow acting like a blanket to keep him warm.
On any other night, these same dark woods would be frightening and threatening, holding potential harm for the poet. But on this night, he finds it fascinating to consider their beauty like a creature of the wild. In contrast, the horse is impatient to continue the journey, realizing that they have stopped at the wrong spot. The horse is looking for the barn, for shelter, for rest, but in the right place, the poet, or the man, is considering laying down in the midst of nature, unprotected.
He is hypnotized by the possibility of just stopping what he is doing and allowing himself to become one with nature. But, the last two lines of the poem indicate that the poet realizes that his duty, responsibility or promises are more important at the moment than his desire for rest.