The main theme of this poem is happiness and feelings of joy inspired by nature that we may have neglected due to our busy lives. The writer expresses how he's wandering alone and then suddenly sees a group of daffodils and how they are blowing so beautifully in the wind, and the sight of that makes him happy. "A poet could not but be gay". "And then my heart with pleasure fills, And dances with the daffodils".