Explain what he regrets and then explain the solution Wordsworth offers to this problem by the end of his poem
In the second stanza the speaker says that even though he can still see the rainbow, the rose, the moon, and the sun, and even though they are still beautiful, something is different...something has been lost: "But yet I know, where'er I go, / That there hath past away a glory from the earth." The speaker is saddened by the birds singing and the lambs jumping in the third stanza. Soon, however, he resolves not to be depressed, because it will only put a damper on the beauty of the season. He declares that all of the earth is happy, and exhorts the shepherd boy to shout.
In the fourth stanza the speaker continues to be a part of the joy of the season, saying that it would be wrong to be "sullen / While Earth herself in adorning, / And the Children are culling / On every side, / In a thousand valleys far and wide."
