The document discusses recurring themes in W.B. Yeats' works. Time is a major theme, often portrayed negatively as the true enemy that damages beauty and causes regret. Death and the afterlife are also frequent themes, with Yeats questioning what comes after and seeking solace in an eventual reunion or renewal. Nature is portrayed both positively and negatively, sometimes as a source of harmony and sometimes volatility. Yeats uses opposites to emphasize concepts that are at odds, like youth and age, or his idealized past and the modern world.