less causes for the stars whenever they persist in saddling the divinity with burdensome tasks. That certain stars are seen to be left behind by others may be because they travel more slowly, though they go the same round as the others ; or it may be that they are drawn back by the same whirling motion and move in the opposite direction ; or again it may be that some travel over a larger and others over a smaller space in making the same revolution. But to lay down as assured a single explanation of these phenomena is worthy of those who seek to dazzle the multitude with marvels. " Falling stars, as they are called, may in some cases be due to the mutual friction of the stars themselves, in other cases to the expulsion of certain parts when that mixture of fire and air takes place which was mentioned when we were discussing lightning ; or it may be due to the meeting of atoms capable of generating fire, which accord so well as to produce this result, and their subsequent motion wherever the impulse which brought them together at first leads them ; or it may be that wind collects in certain dense mist-like masses and, since it is imprisoned, ignites and then bursts forth upon whatever is round about it, and is carried to that place to which its motion impels it. And there are other ways in which this can be brought about without recourse to myths. •• The fact that the weather is sometimes foretold from the behaviour of certain animals is a mere coincidence in time. a For the animals offer no necessary reason why a storm should be produced ; and no divine being sits observing when these animals go out and afterwards fulfilling the signs which they