The speaker is someone with money and experience of city pleasures — the harlot’s arms and wine — yet he sits alone in a green field. The poem gives his answer to that puzzle: Nature matters to him in a way those other pleasures do not. The “pleasure life” leaves him stale and heavy in the morning, with no real rest. The quiet life of Nature, by contrast, wakes fresh and singing, like a lark. He sits alone till noon in a long dream of quiet bliss, sharing the lark’s joy without needing any wine. By the end, he calls Nature’s power a kind of marriage to the Muse, keeping him from the harlot’s arms and the drunkard’s life. The mood is peaceful and content, though a little defensive — as if he is explaining his choice to himself as much as to anyone else.
The Two Lives — Summary
Now how could I, with gold to spare, Who know the harlot's arms, and wine, Sit in this green field all alone, If Nature was not truly mine? That Pleasure life wakes stale at morn, From heavy sleep that no rest brings: This life of quiet joy wakes fresh, And claps its wings at morn, and sings. So here sit I, alone till noon, In one long dream of quiet bliss; I hear the lark and share his joy, With no more winedrops than were his. Such, Nature, is thy charm and power-- Since I have made the Muse my wife-- To keep me from the harlot's arms, And save me from a drunkard's life.