The Meaning of 'Sailing to Byzantium'

Here is the mood of an old poet who knows his worth. The world of his youth belongs to the young, who cannot recognize him. His life and the life that sustains it are ephemeral; he's come to the end of it, and he must travel on into agelessness. This new world is not natural but invented, and to go there he would gladly abandon his natural life. The timeless world he longs for is really the ancient world, the holy city of Byzantium, inhabited by worthies greater than himself. When he gets there, he would like to become one of their beautiful creations, like a golden bird set upon a golden tree. But he knows that when he sings, he will sing again of the natural world, of what is past, or passing, or to come.