De Facie Quae in orbe Lunae Apparet

Speaking generally, he said, I marvel that they adduce against us the moon’s shining upon the earth at the half and at the gibbous and the crescent phases too.[*](i.e. the moon at the half, gibbous, and crescent phases presents such a great difficulty for the Stoics themselves that it is strange for them to adduce these phenomena as refutation of the theory that the moon shines by reflected light. Wyttenbach’s conjecture, ἐκπίπτουσαν for ἐμπίπτουσαν, approved by Purser and apparently adopted by Prickard in his translation of 1918, betrays a misapprehension of the meaning of the text.) After all, if the mass of the moon that is illuminated by the sun were ethereal or fiery, the

sun would not leave her[*](For ἀπέλειπεν cf. 931 C s.v.. The dative with the verb is unobjectionable, cf. e.g. [Reg. et Imp. Apophthegm.] 178 D, 195 F.) a hemisphere that to our perception is ever in shadow and unilluminated; on the contrary, if as he revolves he grazed her ever so slightly, she should be saturated in her entirety and altered through and through by the light proceeding easily in all directions. Since wine that just touches water at its surface[*](For κατὰ πέρας cf. Communibus Notitiis, 1080 E ( = S. V. F. ii, frag, 487): ψαύειν κατὰ πέρας τὰ σώματα λέγουσι and S. V. F. ii, frag. 433 cited in note d on 930 F s.v.. The emendations of Emperius and Papabasileios are consequently ill-advised.) or a drop of blood fallen into liquid at the moment [of contact] stains all the liquid red,[*](cf. Communibus Notitiis, 1078 D - E ( = S. V. F. ii, frag. 480) and S. V. F. ii, frags. 473, 477, 479.) and since they say that the air itself is filled with sunshine not by having any effluences or rays commingled with it but by an alteration and change that results from impact or contact of the light,[*](cf.S. V. F. ii, frag. 433 (Galen, In Hippocr. Epidem. vi Comment. iv, vol. xvii, B, p. 161 [Kühn], especially: τοῖς ἄνω πέρασιν αὐτοῦ (scil. τοῦ ἀέρος) προσπιπτούσης τῆς ἡλιακῆς αὐγῆς ὅλος ἀλλοιοῦταί τε καὶ μεταβάλλεται συνεχὴς ὢν ἑαυτῷ). cf. also note a on 922 E supra.) how do they imagine that a star can come in contact with a star or light with light and instead of blending and producing a thorough mixture and change merely illuminate those portions of the surface which it touches?[*](cf. Cleomedes, ii. 4. 101 (p. 182. 20 ff. [Ziegler]) for the doctrine of Posidonius, which Plutarch here turns against him and the Stoics generally: τρίτη ἐστὶν αἵρεσις ἡ λέγουσα κιρνᾶσθαι αὐτῆς (scil. τῆς σελήνης) τὸ φῶς ἔκ τε τοῦ οἰκείου καὶ τοῦ ἡλιακοῦ φωτὸς καὶ τοιοῦτον γίνεσθαι οὐκ ἀπαθοῦς μενούσης αὐτῆς ἀλλ᾽ ἀλλοιουμένης ὑπὸ τοῦ ἡλιακοῦ φωτὸς καὶ κατὰ τοιαύτην τὴν κρᾶσιν ἴδιον ἰσχούσης τὸ φῶς cf. ibid. 104 (p. 188. 4-7).) In fact, the circle which the sun in its revolution describes and causes to turn about the moon now coinciding with the circle that divides her visible and invisible parts and now standing at right angles to it so as to intersect it and be intersected by it, by different inclinations and relations of the bright part to the dark producing in her the gibbous and crescent phases,[*](cf. Cleomedes, ii. 5. 109-111 (pp. 196. 28-200. 23 [Ziegler]).) conclusively demonstrates that her illumination is the result not of combination but of contact, not of a concentration of light within her but of light shining upon her from without. In that she is not only illuminated herself, however, but also transmits to us the semblance of her illumination, she gives us all the more confidence in our theory of her substance. There are no reflections from anything rarefied or tenuous in texture, and it is not easy even to imagine light rebounding from light or fire from fire; but whatever is to cause a repercussion or a reflection must be compact and solid,[*](Here ἐμβριθές is used as the opposite of λεπτομερές (cf. Liddell and Scott, s.v. ἐμβρίθεια ii) as πυκνόν is of ἀραιόν.) in order that it may stop a blow and repel it.[*](cf. Cleomedes, ii. 4. 101-102 (p. 184. 9-18 [Ziegler]). Cleomedes, assuming that the moon is μανόν, uses this as an argument against reflection; Plutarch, having established the necessity of reflection, uses the argument to support the contention that the moon is earthy.) At any rate, the same sunlight that the air lets pass without impediment or resistance is widely reflected and diffused from wood and stone and clothing exposed to its rays. The earth too we see illuminated by the sun in this fashion. It does not let the light penetrate its depths as water does or pervade it through and through as air does; but such as is the circle of the sun that moves around the moon and so great as is the part of her that it intercepts, just such a circle in turn moves around the earth, always illuminating just so much and leaving another part unilluminated,[*](cf. Cleomedes, ii. 5. 108 (p. 194. 20 ff. [Ziegler]).) for the illuminated portion of either body appears to be slightly greater than a hemisphere.[*](Cleomedes, ii. 5. 109 (p. 198. 6-9 [Ziegler]).) Give me leave then to put it in geometrical fashion in terms of a proportion. Given three things approached by the light from the sun: earth, moon, air; if we see that the moon is illuminated not as the air is rather than as the earth, the things upon which the same agent produces the same effects must be of a similar nature. [*](I have tried to preserve the contorted form in which Plutarch expresses the point that the moon, since it is affected by sunlight as the earth is and not as air is, must have the consistency of earth and not of air.)

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.)

Well now, he said, which of the proofs came after this? And I replied, That the moon is subject to the same eclipse. Thank you, he said, for reminding me; but now shall I assume that you have been persuaded and do hold the moon to be eclipsed by being caught in the shadow and so

turn straightway to my argument,[*](The argument that the moon is earthy, which at the beginning of chap. 19 (931 D) Lucius stated in the form of a proportion.) or do you prefer that I give you a lecture and demonstration in which each of the arguments is enumerated? By heaven, said Theon, do give these gentlemen a lecture. As for me, I want some persuasion as well, since I have only heard it put this way: when the three bodies, earth and sun and moon, get into a straight line, eclipses take place because the earth deprives the moon or the moon, on the other hand, deprives the earth of the sun, the sun being eclipsed when the moon and the moon when the earth takes the middle position of the three, the former of which cases occurs at conjunction and the latter at the middle of the month. [*](cf. Cleomedes, ii. 6. 115 (p. 208. 9-12 [Ziegler]) for the eclipse of the moon and ii. 4. 106 (p. 192, 14-20) for the eclipse of the sun; cf. also Theon of Smyrna, p. 193. 23 ff, and p. 197. 22 ff. (Hiller); Geminus, viii. 14 (p. 104. 23 ff. [Manitius]).) Whereupon Lucius said, Those are roughly the main points, though, of what is said on the subject. Add thereto first, if you will, the argument from the shape of the shadow. It is a cone, as is natural when a large fire or light that is spherical circumfuses a smaller but spherical mass.[*](See notes a and b on 923 B supra.) This is the reason why in eclipses of the moon the darkened parts are outlined against the bright in segments that are curved,[*](cf. Cleomedes, ii. 6. 118 (p. 214. 2-12 [Ziegler]); Aristotle, Caelo, 297 B 23-30.) for whenever two round bodies come into contact the lines by which either intersects the other turn out to be circular since they have everywhere a uniform tendency.[*](i.e. the intersecting lines are always arcs of a circle because the degree of curvature of each of the two surfaces is at every point similar. For this interpretation cf Class. Phil. xlvi (1951), p. 144.) Secondly, I think that you are aware that of the moon the eastward parts are first eclipsed and of the sun the westward parts and that, while the shadow of the earth moves from east to west, the sun and the moon move contrariwise towards the east.[*](cf.Class. Phil. xlvi (1951), p. 144; Cleomedes, ii. 6. 116 (p. 210. 6-19 [Ziegler]), 117 (p. 212. 1-12) on the lunar eclipse; ii. 5. 113-114 (p. 204. 27 ff.) on the solar eclipse; Geminus, xii. 5-13 (pp. 138-140 [Manitius]) on the eastward motion of sun and moon.) This is made visible to sense-perception by the phenomena and needs no very lengthy explanations to be understood, and these phenomena confirm the cause of the eclipse. Since the sun is eclipsed by being overtaken and the moon by encountering that which produces the eclipse, it is reasonable or rather it is necessary that the sun be caught first from behind and the moon from the front, for the obstruction begins from that point which the intercepting body first assails. The sun is assailed from the west by the moon that is striving after him, and she is assailed from the east [by the earth’s shadow] that is sweeping down as it were in the opposite direction. Thirdly, moreover, consider the matter of the duration and the magnitude of lunar eclipses. If the moon is eclipsed when she is high and far from the earth, she is concealed for a little time; but, if this very thing happens to her when she is low and near the earth, she is strongly curbed and is slow to get out of the shadow, although when she is low her exertions of motion are greatest and when she is high they are least. The reason for the difference lies in the shadow, which being broadest at the base, as cones are, and gradually contracting terminates at the vertex in a sharp and fine tip. Consequently the moon, if she has met the shadow when she is low, is involved by it in its largest circles[*](cf. Communibus Notitiis, 1080 B: αὐταὶ γάρ δήπουθεν αἱ τῶν κωνικῶν τμημάτων ἐπιφάνειαι. κύκλοι εἰσίν.) and traverses its deep and darkest part; but above as it were in shallow water by reason of the fineness of the shadow she is just grazed and quickly gets clean away.[*](cf. Cleomedes, ii. 6. 119 (pp. 214. 13-216. 8 [Ziegler]); for the observation that the planets appear to move most swiftly when they are nearest to the earth and most slowly when they are farthest away cf. Cleomedes, ii. 5. 112-114 (pp. 202. 26-206. 27), and Theon of Smyrna, p. 135. 6-11 and p. 157. 2-12 (Hiller). Plutarch’s language, however, implies that the moon makes a conscious exertion to accelerate her motion when she is near the earth, and in the myth at 944 A s.v. it is stated that she increases her speed in order to escape the shadow of the earth. Kepler in note 51 to his translation declares that, contrary to what Lucius here says, perigee eclipses even when central are briefer than apogee eclipses; and Prickard (Plutarch on the Face of the Moon [1911], p. 11) says that ceteris paribus an eclipse of a distant moon should be longer by about one fifteenth. Prof. Neugebauer informs me that, using the Ptolemaic figures for the apparent diameter of the moon and of the earth’s shadowand the classical figures given by Geminus for the velocity, the maximum totality in apogee should be 4; 3, 23ʰʳ and in perigee 3; 20, 0ʰʳ.) I pass over all that was said besides with particular reference to the phases and variations,[*](Probably a reference to such matters as are discussed by Geminus, ix (pp, 124-130 [Manitius]), With τὰς φάσεις καὶ διαφορήσεις cf. species diversitatesque Lunae, Martianus Capella, viii. 871 (p. 459. 15-16 [Dick]).) for these too, in so far as is possible,[*](It is impossible to give an exhaustive and accurately scientific explanation of physical phenomena, for they are involved in the indeterminateness of matter. cf. Aristotle, Anal. Post. 87 a 31-37 and Metaphysics, 995 A 14-17, 1078 A 9-13 (cf. Zeller, Die Philosophie der Griechen, ii. 2, p. 166, n. 3); and for Plato’s more extreme attitude cf. especially Timaeus, 29 B - C, Philebus, 56 and 59. Plutarch appears to have Philebus, 56 C in mind at Quaest. Conviv 744 e-f, where he makes astronomy attendant upon geometry, as he has Philebus, 66 a-b in mind at 720 C (cf. R. M. Jones, Class. Phil. vii [1912], pp. 76 f.). For the notion of the necessary lack of accuracy of the physical sciences cf. further Plat. Quaest. 1001 E ff. and Quaest. Conviv 699 B.) admit the cause alleged; and instead I revert to the argument before us[*](cf. note a on 932 D supra.) which has its basis in the evidence of the senses. We see that from a shadowy place fire glows and shines forth more intensely,[*](cf. Cleomedes, ii. 3. 99 (p. 180. 11-13 [Ziegler]) and ii. 6. 120-121 (p. 218. 2-3).) whether because the dark air being dense does not admit its effluences and diffusions but confines and concentrates the substance in a single place or because this is an affection of our senses that as hot things appear to be hotter in comparison with cold and pleasures more intense in comparison with pains so bright things appear conspicuous when compared with dark, their appearance being intensified by contrast to the different impressions.[*](cf.Quomodo Adul. ab Amico Internosc. 57 C, Herodoti Malignitate, 863 E.) The former explanation seems to be the more plausible, for in sunlight fire of every kind not only loses its brilliance but by giving way becomes ineffective and less keen, the reason being that the heat of the sun disperses and dissipates its potency.[*](cf. Aristotle, Caelo, 305 A 9-13; [Alexander], Anima Libri Mantissa, p. 128. 2-7 (Bruns), and the explanation of the moon’s phases ascribed to Antiphon in Placitis, 891 D = Aëtius, ii. 28. 4 (Dox. Graeci, p. 358).) If, then, as the Stoics themselves assert,[*](See 928 D supra with note d there and 935 B s.v.. Reference to the present passage is omitted in S. V. F. ) the moon, being a rather turbid star, has a faint and feeble fire of her own, she ought to have none of the things happen to her that now obviously do but the very opposite; she ought to be revealed when she is hidden and hidden whenever she is now revealed, that is hidden all the rest of the time when she is bedimmed by the circumambient ether[*](αἰθήρ is here used in the Stoic sense as in 922 B and 928 c-d supra.) but shining forth and becoming brilliantly clear at intervals of six months or again at intervals of five when she sinks under the shadow of the earth, since of 465 ecliptic full moons 404 occur in cycles of six months and the rest in cycles of five months.[*](For this period of 465 ecliptic full moons cf. Class. Phil. xlvi (1951), p. 145.) It ought to have been at such intervals of time then that the moon is revealed resplendent in the shadow, whereas in the shadow she is eclipsed and loses her light but regains it again as soon as she escapes the shadow[*](For this argument cf. Cleomedes, ii. 4. 103 (p. 182. 10-16 [Ziegler]).) and is revealed often even by day, which implies that she is anything but a fiery and star-like body.