Whose that author?

"Had I asked in any of those cities, would anyone have believed they someday would lie in ruins? Each age is an age that is passing, and cities, my friend, are transitory things. Each is born from the dust; each matures, grows older, then it fades and dies. A passing traveler looks at a mound of sand and broken stones and asks 'What was here?' and his answer is only an echo or a wind drifting sand."