Similarly curious ideas we shall find to have prevailed with respect to the meaning of everything that they observed in the heavens: thus what a number of opinions have been hazarded on the nature of the "Milky Way" alone! some of which we may learn from Plutarch. The Milky Way, he says, is a nebulous circle, which constantly appears in the sky, and which owes its name to its white appearance. Certain Pythagoreans assert that when Phaeton lit up the universe, one star, which escaped from its proper place, set light to the whole space it passed over in its circular course, and so formed the Milky Way. Others thought that this circle was where the sun had been moving at the beginning of the world. According to others it is but an optical phenomenon produced by the reflection of the sun's rays from the vault of the sky as from a mirror, and comparable with the effects seen in the rainbow and illuminated clouds. Metrodorus says it is the mark of the sun's passage which moves along this circle. Parmenidas pretends that the milky colour arises from a mixture of dense and rare air. Anaxagoras thinks it an effect of the earth's shadow projected on this part of the heavens, when the sun is below. Democritus says that it is the lustre of several little stars which are very near together, and which reciprocally illuminate each other. Aristotle believes it to be a vast mass of arid vapours, which takes fire from a glowing tress, above the region of the ether, and far below that of the planets. Posidonius says that the circle is a compound of fire less dense than that of the stars, but more luminous. All such opinions, except that of Democritus, are of little value, because founded on nothing; perhaps the worst is that of Theophrastus, who said it was the junction between the two hemispheres, which together formed the vault of heaven: and that it was so badly made that it let through some of the light that he supposed to exist everywhere behind the solid sky. We now know that the Milky Way, like many of the nebulae, is an immense agglomeration of suns. The Milky Way is itself a nebula, a mass of sidereal systems, with our own among them, since our sun is a single star in this vast archipelago of eighteen million orbs. The Greeks called it the Galaxy. The Chinese and Arabians call it the River of Heaven. It is the Path of Souls among the North American Indians, and the Road of S. Jacques de Compostelle among French peasants.