The quick answer to this question: Nature!

"The Lake Isle of Innisfree" by Yeats juxtaposes the place the poem is describing—an idyllic place immersed in nature—versus the reality of where the speaker is actually standing which is a busy, urban place. The poem is seemingly a call for a return to Nature, but the reader has to note that the speaker is not really acting on his impulse, he “stands on the roadway/pavements” and listens to the sound of the lake water lapping deep in his “heart’s core.”

In "The world is too much with us" Wordsworth makes a similar cry for a return to nature: "The world is too much with us; late and soon,Getting and spending, we lay waste our powers;Little we see in Nature that is ours; We have given our hearts away, a sordid boon!"