Frost claimed to have written this in a single sitting, early morning, after working all night on another poem. A man stops his horse to watch the woods fill up with snow; the horse finds it strange; the man has promises to keep and miles to go before he sleeps. The repetition of the final lines has invited endless interpretation: sleep as death, as rest, as simple sleep. Frost refused to explain. The poem is simple enough for children and mysterious enough for a lifetime. The woods are lovely, dark and deep. The promises remain unkept.