As he sits in his green bower among the primrose tufts and periwinkles, the speaker affirms his belief that every flower enjoys the air that it breathes. This attribution of human feelings and responses to non-human objects like flowers is an example of what's called the pathetic fallacy, which was a common feature of Romantic poetry in general and Wordsworth's poetry in particular.

Wordsworth didn't just admire nature for its beauty; he saw it as having a life of its own. What's more, he believed that human beings are part of that life, joined together with rocks, trees, plants, and flowers in a gigantic organism that encompasses all forms of life on earth. As Wordsworth says in the second stanza of "Lines Written in Early Spring," the human soul is linked to the fair—that is to say, beautiful—works of nature. Yet despite being part of the same beautiful world as the flowers, the primrose tufts and periwinkles, man has created so much in this world that is very far from beautiful, and this brings sad thoughts to the speaker's mind.