What lines?. There’s not enough information
Life in an imagined cottage at Innisfree is peaceful, idyllic, happy. Bees and crickets buzz and sing, there are various colors and nuances of life. On the other hand, the speaker's current life is dreary and grey, which we suspect even from the beginning, but the speaker confirms it explicitly in the last two lines. He dreams of a different life while he is stuck in the colorless, grim reality of the urban environment where he lives.
Answer: A Journey
Explanation: Expedition means an adventure or it can be as simple as a flight on a plane but either way a journey seems like the right meaning for the word expedition.
