De Facie Quae in orbe Lunae Apparet

When all had applauded Lucius, I said: Congratulations upon having added to an elegant account an elegant proportion, for you must not be defrauded of what belongs to you, He smiled thereat and said: Well then proportion must be used a second time, in order that we may prove the moon to be like the earth not only because the effects of the same agent are the same on both but also because the effects of both on the same patient are the same. Now, grant me that nothing that happens to the sun is so like its setting as a solar eclipse. You will if you call to mind this conjunction recently which, beginning just after noonday, made many stars shine out from many parts of the sky[*](Concerning this eclipse see the Introduction, § 3 supra on the date of the dialogue.) and tempered the air in the manner of twilight.[*](For λυκανγές see 941 D s.v. and Lucian, Vera Hist. ii, 12. Prickard takes the κρᾶσις to refer to the degree of heat; Raingeard, like Amyot and Wyttenbach, takes it to refer to colour or light. Either is possible, but I think a reference to colour the more probable; for κρᾶσις used of colour cf. Quaest. Conviv 647 c.) If you do not recall it, Theon here will cite us Mimnermus[*](cf.Anthologia Lyrica Graeca, ed. Diehl², i. 1, pp. 50-57, and Edmonds, Elegy and Iambus, i, pp. 82-103; Mimnermus is mentioned in the pseudo-Plutarchean Musica, chap. 8, 1133 f.) and Cydias[*](cf. Plato, Charmides, 155 d; Edmonds, Lyra Graeca, iii, p. 68; Wilamowitz, Textgeschichte der griechischen Lyriker, p. 40, n. 1.) and

Archilochus[*](cf. Archilochus, frag. 74 (Anthologia Lyrica Graeca, ed. Diehl², i. 3, p. 33 = Edmonds, Elegy and Iambus, ii, p. 134).) and Stesichorus besides and Pindar,[*](cf. Pliny, Nat. Hist. ii. 12, § 54: quo in metu fuisse Stesichori et Pindari vatum sublimia ora palam est deliquio solis. ) who during eclipses bewail the brightest star bereft [*](= Pindar, Paean, ix. 2-3: ἄστρον ὑπέρτατον ἐν ἁμέρᾳ κλεπτόμενον. ) and at midday night falling [*](Possibly Stesichorus, cf. Bergk, Poetae Lyrici Graeci⁴ , iii, p. 229 (frag. 73), and Edmonds, Elegy and Iambus, i, p. 102, n. 1.) and say that the beam of the sun [is sped] the path of shade [*](cf. Pindar, Paean, ix. 5: ἐτίσκοτον ἀτραπὸν ἐσσυμένα. For the genitive σκότους cf. Audiendis Poetis, 36 E, and Latenter Vivendo, 1130 B.); and to crown all he will cite Homer, who says the faces of men are covered with night and gloom[*](Adapted from Odyssey, xx. 351-352.) and the sun has perished out of heaven[*](Odyssey, xx. 356-357.) speaking with reference to the moon and [hinting that] this naturally occurs

When waning month to waxing month gives say.[*](Odyssey, xix. 307. For this interpretation of the Homeric lines cf. Vita et Poesi Homer, chap. 108 (vii, p. 388. 15 ff. [Bernardakis]), and Heraclitus, Quaestiones Homericae, § 75 (pp. 98. 20-99. 18 [Oelmann]).)

For the rest, I think that it has been reduced by the precision of mathematics to the [clear] and certain [formula] that night is the shadow of earth[*](cf. Primo Frigido, 953 A and Plat. Quaest. 1006 F, where on Timaeus, 40 C Plutarch quotes Empedocles to this effect. Aristotle refers to the definition, Topics, 146 B 28 and Meteorology, 345 B 7-8.) and the eclipse of the sun is the shadow of the moon[*](cf. the lines of Empedocles quoted at 929 c-d supra. In Placitis, 890 F = Aëtius, ii. 24. 1 this explanation of solar eclipses is ascribed to Thales — quite unhistorically, as the subsequent entries show.) whenever the visual ray encounters it. The fact is that in setting the sun is screened from our vision by the earth and in eclipse by the moon; both are cases of occultation, but the vespertine is occultation by the earth and the ecliptic by the moon with her shadow intercepting the visual ray.[*](cf. Cleomedes, ii. 3. 94-95 (p. 172. 6-10 [Ziegler]) and ii. 4. 106 (p. 192. 16-24); Geminus, x (pp. 130. 11-132. 12 [Manitius]).) What follows from this is easy to perceive. If the effect is similar, the agents are similar, for it must be the same agents that cause the same things to happen to the same subject. Nor should we marvel if the darkness of eclipses is not so deep or so oppressive of the air as night is. The reason is that the body which produces night and that which produces the eclipse while the same in substance are not equal in size. In fact the Egyptians, I think, say that the moon is one seventy-second part (of the earth),[*](I know of no other reference to such an estimate.) and Anaxagoras that it is the size of the Peloponnesus[*](According to Hippolytus, Refut. i. 8. 6-10 ( = Dox. Graeci, p. 562 = Anaxagoras, frag. A 42 [ii, p. 16. 16-31, Diels-Kranz]), Anaxagoras said that the sun exceeds the Peloponnesus in size (cf. Aëtius, ii. 21. 3 and Diogenes Laertius, ii. 8). The statement here concerning the moon is missing from Diels-Kranz.); and Aristarchus demonstrates that the ratio of [the earth’s diameter to] the diameter of the moon is smaller than 60 to 19 and greater than 108 to 43.[*](This is Proposition 17 of Aristarchus’s essay, On the Sizes and Distances of the Sun and Moon (cf. Heath’s edition and translation in his Aristarchus of Samos, pp. 351 ff.). Although Plutarch does not say that this contradicts Stoic doctrine, the older, orthodox Stoics held that the moon as well as the sun is larger than the earth ( Placitis, 891 C = Aëtius, ii. 26. 1 = S. V. F. ii, frag. 666; cf. Pliny, Nat. Hist. ii. 11 [8]. 49).) Consequently the earth because of its size removes the sun from sight entirely, for the obstruction is large and its duration is that of the night. Even if the moon, however, does sometimes cover the sun entirely, the eclipse does not have duration or extension; but a kind of light is visible about the rim which keeps the shadow from being profound and absolute.[*](cf. Cleomedes, ii. 4. 105 (p. 190. 17-26).) The ancient Aristotle gives this as a reason besides some others why the moon is observed in eclipse more frequently than the sun, saying that the sun is eclipsed by interposition of the moon but the moon [by that of the earth, which is much larger].[*](= Aristotle, frag. 210 (Rose). The reference is not to Caelo, 293 B 20-25, for in that passage Aristotle gives not his own opinion but that of some Pythagoreans (cf. Cherniss, Aristotles Criticism of Presocratic Philosophy, pp. 198-199, and Aëtius, ii. 29. 4 cited there). For the terminology σελήνης or γῆς ἀντίφραξις cf. Aristotle, Anal. Post. 90 a 15-18, and with the whole passage cf. Pseudo-Alexander, Problem. 2. 46 (quoted by Rose, Aristoteles Pseudepigraphus, § 194, p. 222), and Philoponus, In Meteor. p. 15. 21-23.) Posidonius gave this definition: The following condition is an eclipse of the sun, conjunction of the moon’s shadow with whatever [parts of the earth it may obscure], for there is an eclipse only for those whose visual ray the shadow of the moon intercepts and screens from the sun[*](cf. Cleomedes, ii. 3. 94-95 (p. 172. 6-17 [Ziegler]) and 98 (p. 178. 13-24), ii. 4. 106 (p. 192. 14-20).); — since he concedes then that a shadow of the moon falls upon us, he has left himself nothing to say that I can see. Of a star there can be no shadow, for shadow means the unlighted and light does not produce shadow but naturally destroys it.[*](Posidonius ranked the moon as a star; cf. Arius Didymus, Epitome, frag. 32 (Dox. Graeci, p. 466. 18-21), and Edelstein, A. J. P. lvii (1936), p. 297. For the theory that the light of the moon is a product of her own proper light and the solar light which produces an alteration in her cf. Cleomedes, ii. 4.101 (pp. 182. 20-184. 3 [Ziegler]) and 104 (p. 188. 5-27), the latter of which indicates how the present contention of Plutarch could have been answered from the point of view of Posidonius.)