Welcome to Episode One Hundred Thirty of Lucretius Today.
This is a podcast dedicated to the poet Lucretius, who wrote "On The Nature of Things," the only complete presentation of Epicurean philosophy left to us from the ancient world.
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Today we continue Epicurus' Letter to Pythocles and we look at more phenomena of the sun and moon. Now let's join Martin reading today's text:
 The wanings of the moon and its subsequent waxings might be due to the revolution of its own body, or equally well to successive conformations of the atmosphere, or again to the interposition of other bodies; they may be accounted for in all the ways in which phenomena on earth invite us to such explanations of these phases; provided only one does not become enamoured of the method of the single cause and groundlessly put the others out of court, without having considered what it is possible for a man to observe and what is not, and desiring therefore to observe what is impossible. Next the moon may have her light from herself or from the sun.
 For on earth too we see many things shining with their own, and many with reflected light. Nor is any celestial phenomenon against these explanations, if one always remembers the method of manifold causes and investigates hypotheses and explanations consistent with them, and does not look to inconsistent notions and emphasize them without cause and so fall back in different ways on different occasions on the method of the single cause. The impression of a face in the moon may be due to the variation of its parts or to interposition or to any one of many causes which might be observed, all in harmony with phenomena.
 For in the case of all celestial phenomena this process of investigation must never be abandoned - for if one is in opposition to clear-seen facts, he can never have his part in true peace of mind.
The eclipse of sun and moon may take place both owing to their extinction, as we see this effect is produced on earth, or again by the interposition of some other bodies, either the earth or some unseen body or something else of this sort. And in this way we must consider together the causes that suit with one another and realize that it is not impossible that some should coincide at the same time.
 Next the regularity of the periods of the heavenly bodies must be understood in the same way as such regularity is seen in some of the events that happen on earth. And do not let the divine nature be introduced at any point into these considerations, but let it be preserved free from burdensome duties and in entire blessedness. For if this principle is not observed, the whole discussion of causes in celestial phenomena is in vain, as it has already been for certain persons who have not clung to the method of possible explanations, but have fallen back on the useless course of thinking that things could only happen in one way, and of rejecting all other ways in harmony with what is possible, being driven thus to what is inconceivable and being unable to compare earthly phenomena, which we must accept as indications.
 The successive changes in the length of nights and days may be due to the fact that the sun’s movements above the earth become fast and then slow again because he passes across regions of unequal length or because he traverses some regions more quickly or more slowly, (or again to the quicker or slower gathering of the fires that make the sun), as we observe occurs with some things on earth, with which we must be in harmony in speaking of celestial phenomena. But those who assume one cause fight against the evidence of phenomena and fail to ask whether it is possible for men to make such observations.
 The waning of the moon and again her waxing might be due to the rotation of the moon's body, and equally well to configurations which the air assumes; further, it may be due to the interposition of certain bodies. In short, it may happen in any of the ways in which the facts within our experience suggest such an appearance to be explicable. But one must not be so much in love with the explanation by a single way as wrongly to reject all the others from ignorance of what can, and what cannot, be within human knowledge, and consequent longing to discover the indiscoverable. Further, the moon may possibly shine by her own light, just as possibly she may derive her light from the sun;
 For in our own experience we see many things which shine by their own light and many also which shine by borrowed light. And none of the celestial phenomena stand in the way, if only we always keep in mind the method of plural explanation and the several consistent assumptions and causes, instead of dwelling on what is inconsistent and giving it a false importance so as always to fall back in one way or another upon the single explanation. The appearance of the face in the moon may equally well arise from interchange of parts, or from interposition of something, or in any other of the ways which might be seen to accord with the facts.
 For in all the celestial phenomena such a line of research is not to be abandoned; for, if you fight against clear evidence, you never can enjoy genuine peace of mind.
An eclipse of the sun or moon may be due to the extinction of their light, just as within our own experience this is observed to happen; and again by interposition of something else – whether it be the earth or some other invisible body like it. And thus we must take in conjunction the explanations which agree with one another, and remember that the concurrence of more than one at the same time may not impossibly happen. He says the same in Book XII. of his "De Natura," and further that the sun is eclipsed when the moon throws her shadow over him, and the moon is eclipsed by the shadow of the earth; or again, eclipse may be due to the moon's withdrawal, and this is cited by Diogenes the Epicurean in the first book of his "Epilecta."
 "And further, let the regularity of their orbits be explained in the same way as certain ordinary incidents within our own experience; the divine nature must not on any account be adduced to explain this, but must be kept free from the task and in perfect bliss. Unless this be done, the whole study of celestial phenomena will be in vain, as indeed it has proved to be with some who did not lay hold of a possible method, but fell into the folly of supposing that these events happen in one single way only and of rejecting all the others which are possible, suffering themselves to be carried into the realm of the unintelligible, and being unable to take a comprehensive view of the facts which must be taken as clues to the rest.
 The variations in the length of nights and days may be due to the swiftness and again to the slowness of the sun's motion in the sky, owing to the variations in the length of spaces traversed and to his accomplishing some distances more swiftly or more slowly, as happens sometimes within our own experience; and with these facts our explanation of celestial phenomena must agree; whereas those who adopt only one explanation are in conflict with the facts and are utterly mistaken as to the way in which man can attain knowledge.