Attar's best known work is called Mantiq-ut-Tayr; or the Colloquy of the Birds, from which the idea of the Blue Bird has been taken today. Very few have understood the idea of the Blue Bird, or the Bird of the Sky. It contains a very ancient teaching, through the use of the Persian word for sky. This teaching points out that every soul has a capacity which may be called the sky, and this capacity can accommodate the earth or heaven, whichever it partakes of and holds within itself. When one walks in a crowd what does one see? One sees numerous faces, but one might better call them various attitudes. All that we see in individuals, all that presents itself to us, has expression, atmosphere and form. If we give it one name, it is the attitude, whatever attitude they have towards life, right or wrong, good or bad; they are themselves that attitude. Does this not show how appropriate the word sky is?