William Butler Yeats - Anima Mundi (Chap.26) lyrics

Because even the most wise dead can but arrange their memories as we arrange pieces upon a chess-board and obey remembered words alone, he who would turn magician is forbidden by the Zoroastrian oracle to change “barbarous words” of invocation. Communication with Anima Mundi is through the a**ociation of thoughts or images or objects; and the famous dead and those of whom but a faint memory lingers, can still—and it is for no other end that, all unknowing, we value posthumous fame—tread the corridor and take the empty chair. A glove or a name can call their bearer; the shadows come to our elbow amid their old undisturbed habitations, and “materialisation” itself is easier, it may be, among walls, or by rocks and trees, that carry upon them particles the vehicles cast off in some extremity while they had still animate bodies. Certainly the mother returns from the grave, and with arms that may be visible and solid, for a hurried moment, can comfort a neglected child or set the cradle rocking; and in all ages men have known and affirmed that when the soul is troubled, those that are a shade and a song: “live there, And live like winds of light on dark or stormy air.”