A bouncer should have carded Keats every time he took a walk outdoors. "My name is John Keats, and I'm a nature-holic." No one else we know of becomes so intoxicated simply from the sights, sounds, and smells of nature. Don't just take our word for it. Check out his other poetry. In "Ode to a Nightingale" Keats describes his need for a "draught of vintage" (a glass of wine) that tastes likes "Flora and the country-green." In the "Ode on Melancholy" he laments the "poisonous wine" of an herb called "Wolf's-bane." In "To Autumn," he describes autumn as "drowsed with the fume of poppies." Poppies are used to create opium, so we're fairly sure he's making a drug reference here. But he's also simply pointing out the effect of smelling flowers. He finds nature intoxicating.