It has been said that where poets area concerned that the moral and the aesthetic are rarely separate entitites. This is certainly evident in Hardy's poem. He seems to move between the real and the ideal life, with a bittersweet mood, explaining that human joy is fleeting and is often eroded by time, wind, rain, and the elements. And, then, the poet moves from the real to the sublime seeming to muse about the permanence, or impermanence of art (in particular poetry), and what will make it stand the test of time. The answer? A poem lasts if the idea and theme that it expresses is enduring and universal to many. Since we still read Hardy's works to this day, it could be that his theory was correct.