Vitae philosophorum

Diogenes Laertius

Diogenes Laertius. Hicks, R. D., editor. Cambridge, MA.: Harvard University Press; London: William Heinemann Ltd., 1925.

And this happens at certain parts either because a current has forced its way in from without or because the heat has gained possession of certain passages in order to effect this.

Comets arise either because fire is nourished in

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certain places at certain intervals in the heavens, if circumstances are favourable; or because at times the heaven has a particular motion above us so that such stars appear; or because the stars themselves are set in motion under certain conditions and come to our neighbourhood and show themselves. And their disappearance is due to the causes which are the opposite of these.

Certain stars may revolve without setting not only for the reason alleged by some, because this is the part of the world round which, itself unmoved, the rest revolves, but it may also be because a circular eddy of air surrounds this part, which prevents them from travelling out of sight like other stars; or because there is a dearth of necessary fuel farther on, while there is abundance in that part where they are seen to be. Moreover there are several other ways in which this might be brought about, as may be seen by anyone capable of reasoning in accordance with the facts. The wanderings of certain stars, if such wandering is their actual motion, and the regular movement of certain other stars,

may be accounted for by saying that they originally moved in a circle and were constrained, some of them to be whirled round with the same uniform rotation and others with a whirling motion which varied; but it may also be that according to the diversity of the regions traversed in some places there are uniform tracts of air, forcing them forward in one direction and burning uniformly, in others these tracts present such irregularities as cause the motions observed. To assign a single cause for these effects when the facts suggest several causes is madness and a strange inconsistency; yet it is done by adherents of rash astronomy, who assign meaningless

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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.[*](Cf.§ 98, The same topic is now treated again. Usener, who attributed this whole epistle to a compiler, believed that both passages were taken from the same part of Epicurus’s On Nature.) 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

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have given.

For such folly as this would not possess the most ordinary being if ever so little enlightened, much less one who enjoys perfect felicity.

All this, Pythocles, you should keep in mind; for then you will escape a long way from myth, and you will be able to view in their connexion the instances which are similar to these. But above all give yourself up to the study of first principles and of infinity and of kindred subjects, and further of the standards and of the feelings and of the end for which we choose between them. For to study these subjects together will easily enable you to understand the causes of the particular phenomena. And those who have not fully accepted this, in proportion as they have not done so, will be ill acquainted with these very subjects, nor have they secured the end for which they ought to be studied.