Robert Frost employs the crow and the hemlock tree—symbols typically associated with gloom, fear, and poison—to act as catalysts for a positive change. Initially, the poet is in a state of 'rue' or regret, feeling that his day is wasted. However, when the crow shakes down the 'dust of snow' from the hemlock tree onto him, the sudden, cold touch of nature breaks his meditative sadness. This simple incident changes his mood from depressive to appreciative, saving the rest of his day from being wasted. The poem thus conveys that even small, seemingly insignificant or 'negative' elements of nature can bring about a significant positive transformation in a human's perspective.