Lines written in early spring

I heard a thousand blended notes, While in a grove I sat reclined, In that sweet mood when pleasant thoughts Bring sad thoughts to the mind. To her fair works did Nature link The human soul that through me ran: And much it grieved my heart to think What man has made of man. Through primrose tufts, in that green bower, The periwinkle trailed its wreaths; And 'tis my faith that every flower Enjoys the air it breathes. The birds around me hopped and played, Their thoughts I cannot measure: But the least motion which they made It seemed a thrill of pleasure. The budding twigs spread out their fan, To catch the breezy air; And I must think, do all I can, That there was pleasure there. If this belief from heaven be sent, If such be Nature's holy plan, Have I not reason to lament What man has made of man?