One of Yeats's early poems, "The Lake Isle of Innisfree" seems to suggest a thesis of peaceful independence attainable through a harmonious and near-ascetic identification with nature. The proposed journey to the lake-isle at the eastern end of Lough Gill in Country Sligo is an imaginative escape to a place of dreamy solitude of the poet's boyhood. Living all alone in the midst of nature where "peace comes dropping slow," living in the clay-cabin with the "nine bean rows" and a bee-hive, living in a "bee-loud glade" through the purple noon, the evening "full of linnet's wings," and the midnight "all a glimmer," the poet conceives a sharp contrast between London and Sligo, a contrast between the urban and the rural, between the metropolitan and the pastoral. This is very much like the central Romantic thesis of the "Return to Nature."
The main thesis (or main theme) of the poem "The Lake Isle of Innisfree" is about the author's dreams of returning back to the "peaceful" nature, to a place of deep relaxation and rehabilitation of the soul and the mental mind, and to escape from the chaotic and deeply corrupted civilization of the modern society, which global citizens pursuing material comforts and natural bodily needs using unscrupulous methods, to control their entire life, to "enrich" their life. The poet was trying to create a distinct harmony with nature, comparing it with the self-sufficient, solitary life of his. He despised the working population on pursuing material needs to monopolize their life.
There are several subtly different ways to interpret "The Lake Isle of Innisfree," often considered one of the poet's most enchanting lyric poems. The main focus of the poem, however, is on the speaker's desire to return and reconnect with nature. Nature here is presented as a place of solace--a place where truth will emerge and the speaker can return to a life that is more meaningful.
It is well known that Yeats was influenced by Thoreau's Walden, and indeed some of Thoreau's ideas about living in harmony with nature might be incorporated in the poet's narrative.