Plutarch, De Facie Quae in orbe Lunae Apparet, Harold Cherniss (Translator), William C. Helmbold (Translator), 18

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[18] 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.¹ After all, if the mass of the moon that is illuminated by the sun were ethereal or fiery, the sun would not leave her² 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 surface³ or a drop of blood fallen into liquid at the moment [of contact] stains all the liquid red,⁴ 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,⁵ 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?⁶ 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,⁷ 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,⁸ in order that it may stop a blow and repel it.⁹ 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,¹⁰ for the illuminated portion of either body appears to be slightly greater than a hemisphere.¹¹ 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.¹²

De Facie Quae in orbe Lunae Apparet. Plutarch. Harold Cherniss (Translator), William C. Helmbold (Translator). Cambridge, MA. 1957.

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Funding provided by The National Endowment for the Humanities.

Current edition Perseus

Concerning the Face which Appears in the Orb Of the Moon (English) (Plutarch. Moralia, Vol. XII. Cherniss, Harold and William Clark Helmbold translators. Cambridge, MA: Harvard University Press; London: William Heinemann Ltd., 1957 (printing).)

Editions (1)

Περὶ τοῦ ἐμφαινομένου προσώπου τῷ κύκλῳ τῆς σελήνης Perseus (Plutarch. Plutarchi Chaeronensis Moralia, Vol. V. Vernardakēs, Grēgorios N., editor. Leipzig: Teubner, 1893.) — 18 focus

[18] τὸ δʼ ὅλον ἔφη θαυμάζω πῶς τὴν διχότομον ἐφʼ ἡμᾶς κινοῦσιν, ἐμπίπτουσαν μετὰ τῆς ἀμφικύρτου καὶ τῆς μηνοειδοῦς. εἰ γὰρ αἰθέριον 25 930f ὄγκον ἢ πύρινον ὄντα τὸν τῆς σελήνης ἐφώτιζεν ὁ ἥλιος, οὐκ ἂν ἀπέλειπεν αὐτῆς σκιερὸν ἀεὶ καὶ ἀλαμπὲς ἡμισφαίριον πρὸς αἴσθησιν, ἀλλʼ εἰ καὶ κατὰ μικρὸν ἔψαυε περιιών, ὅλην ἀναπίμπλασθαι καὶ διʼ ὅλης τρέπεσθαι τῷ φωτὶ πανταχόσε χωροῦντι διʼ εὐπετείας ἦν προσῆκον. ὅπου γὰρ οἶνος ὕδατος 5 θιγὼν κατὰ πέρας, καὶ σταγὼν αἵματος εἰς ὑγρὸν ἐμπεσόντος, ἀνέχρωσε πᾶν ἅμα φοινιχθέν· αὐτὸν δὲ τὸν ἀέρα λέγουσιν οὐκ ἀπορροαῖς τισὶν οὐδʼ ἀκτῖσι μεμιγμέναις ἀλλὰ τροπῇ καὶ μεταβολῇ κατὰ νύξιν ἢ ψαῦσιν ἀπὸ τοῦ φωτὸς ἐξηλιοῦσθαι· πῶς 10 ἄστρον ἄστρον καὶ φῶς φωτὸς ἁψάμενον οἴονται μὴ κεράννυσθαι, μηδὲ σύγχυσιν ποιεῖν διʼ ὅλου καὶ μεταβολὴν ἀλλʼ ἐκεῖνα φωτίζειν μόνον, ὧν ἅπτεται 931a κατὰ τὴν ἐπιφάνειαν; ὃν γὰρ ὁ ἥλιος περιιὼν κύκλον ἄγει καὶ περιστρέφει περὶ τὴν σελήνην, νῦν μὲν 15 ἐπιπίπτοντα τῷ διορίζοντι τὸ ὁρατὸν αὐτῆς καὶ τὸ ἀόρατον, νῦν δʼ ἀνιστάμενον πρὸς ὀρθὰς, ὥστε τέμνειν ἐκείνου ὑπʼ ἐκείνου τε τέμνεσθαι, καὶ ἄλλαις κλίσεσι καὶ σχέσεσι τοῦ λαμπροῦ πρὸς τὸ σκιερὸν ἀμφικύρτους καὶ μηνοειδεῖς ἀποδιδόντα μορφὰς ἐν 20 αὐτῇ, παντὸς μᾶλλον ἐπιδείκνυσιν · οὐ σύγκρασιν ἀλλʼ ἐπαφήν, οὐδὲ σύλλαμψιν ἀλλὰ περίλαμψιν 931b αὐτῆς ὄντα; τὸν φωτισμόν. ἐπεὶ δʼ οὐκ αὐτὴ φωτίζεται μόνον ἀλλὰ καὶ δεῦρο τῆς αὐγῆς ἀναπέμπει τὸ εἴδωλον, ἔτι καὶ μᾶλλον ἰσχυρίσασθαι τῷ λόγῳ περὶ τῆς οὐσίας δίδωσιν. αἱ γὰρ ἀνακλάσεις γίγνονται πρὸς οὐδὲν ἀραιὸν οὐδὲ λεπτομερές, οὐδʼ ἔστι φῶς ἀπὸ φωτὸς ἢ πῦρ ἀπὸ πυρὸς ἀφαλλόμενον νοῆσαι ῥᾴδιον· ἀλλὰ δεῖ τὸ ποιῆσον ἀντιτυπίαν τινὰ 5 καὶ κλάσιν ἐμβριθὲς εἶναι καὶ πυκνόν, ἵνα πρὸς αὐτὸ πληγὴ καὶ ἀπʼ αὐτοῦ φορὰ γένηται. τὸν γοῦν αὐτὸν ἥλιον ὁ μὲν ἀὴρ διίησιν οὐ παρέχων ἀνακοπὰς οὐδʼ ἀντερείδων, ἀπὸ δὲ ξύλων καὶ λίθων καὶ ἱματίων εἰς φῶς τιθεμένων πολλὰς ἀντιλάμψεις 10 καὶ περιλάμψεις ἀποδίδωσιν. οὕτω δὲ καὶ τὴν γῆν· 931c ὁρῶμεν ὑπʼ αὐτοῦ φωτιζομένην· οὐ γὰρ εἰς βάθος ὥσπερ ὕδωρ οὐδὲ διʼ ὅλης ὥσπερ ἀὴρ διίησι τὴν αὐγήν· ἀλλʼ οἷος τὴν σελήνην περιστείχει κύκλος αὐτοῦ καὶ ὅσον ὑποτέμνεται μέρος ἐκείνης, τοιοῦτος 15 ἕτερος; περίεισι τὴν γῆν καὶ τοσοῦτον φωτίζων ἀεὶ καὶ ἀπολείπων ἕτερον ἀφώτιστον· ἡμισφαιρίου γὰρ ὀλίγῳ δοκεῖ μεῖζον εἶναι τὸ περιλαμπόμενον ἑκατέρας. δότε δή μοι γεωμετρικῶς εἰπεῖν πρὸς ἀναλογίαν, ὡς εἰ, τριῶν ὄντων οἷς τὸ ἀφʼ ἡλίου 20 φῶς πλησιάζει, γῆς σελήνης; ἀέρος, ὁρῶμεν οὐχ ὡς ὁ ἀὴρ μᾶλλον ἢ ὡς ἡ γῆ φωτιζομένην τὴν σελήνην, ἀνάγκη φύσιν ἔχειν ὁμοίαν ἃ ταὐτὰ πάσχειν ὑπὸ ταὐτοῦ πέφυκεν.

Translations (1)

Of the Face Appearing Within the Orb Of the Moon Perseus (Plutarch. Plutarch's Morals, Vol. V. Goodwin, William W., editor; G., A., translator. Boston: Little, Brown, and Company; Cambridge: Press of John Wilson and Son, 1874.) — 18 focus

[18] But in brief, said he, I wonder how they come thus to allege against us the half-moon, there being the same reason when she is gibbous and crescent. For if the sun enlightened the moon, as a mass of ethereal or fiery matter, he would never surely leave one hemisphere, or half of her globe always appearing dark and shadowy to sense, as it is seen to be; but how little soever he touched her superficies, it would be agreeable to reason that it should be wholly replenished and totally changed by that light of his, which by reason of its agility and swiftness so easily spreads and passes through all. For, since wine touching water only in one point, or one drop of blood falling into any liquor, dyes and colors it all with a red or purple color; and since they say, that the very air is altered and changed with light, not by any defluxions or beams intermingled, but by a sudden conversion and change made in one only point; how can they imagine that one star touching another star, and one light another light, should not be immediately mingled, nor make any thorough confusion or change, but only exteriorly illuminate that whose superficies it touches? For that circle which the sun makes by fetching a compass and turning towards the moon,—sometimes falling upon the very line that distinguishes her visible part from her invisible, and sometimes rising up directly, so that it cuts her in two and is reciprocally cut by her, causing in her, by several inclinations and habitudes of the luminous to the dark, those various forms by which she appears gibbous and crescent,—that more than any thing else demonstrates, that all this illumination of the moon is not a mixture, but only a touching; nor a conflux or gathering together of sundry lights, but only an illustration round about.

But forasmuch as she is not only enlightened herself, but also sends back hither the image of her illumination, this confirms us yet further in what we say touching her substance. For reflections and reverberations are not made upon any thing which is rare, and of thin and subtile parts; nor is it easily to be imagined how light can rebound from light, or one fire from another. But that which is to make the reverberation or reflection must be solid and firm, that a blow may be given against it and a rebounding made from it. As a proof of this, we see that the air transmits the sun, and gives him a way to pierce quite through it, not obstructing or driving back his rays; but on the contrary from wood, stones, or clothes put in the sun, there are made many reflections of light and many illuminations round about. So we see that the earth is illuminated by him, not to the very bottom, as the water, nor thoroughly and all over, as the air, through which the beams of the sun have a clear passage; but just such a circle as surrounds the moon surrounds also the earth; and as much of the earth as this circle includes, so much does the sun enlighten, the rest being left without light; for what is illuminated both in the one and in the other is little more than an hemisphere. Permit me therefore now to conclude after the manner of geometricians by proportions. If there are three things which the light of the sun approaches, the air, the moon, and the earth, and if we see that the moon is enlightened by him, not as the air, but as the earth, it is of necessity that those two things must have one and the same nature, which of one and the same cause suffer the same effects.

Notes on the current edition

Concerning the Face which Appears in the Orb Of the Moon

1. 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.

2. 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.

3. 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.

4. cf. Communibus Notitiis, 1078 D - E ( = S. V. F. ii, frag. 480) and S. V. F. ii, frags. 473, 477, 479.

5. 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.

6. 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).

7. cf. Cleomedes, ii. 5. 109-111 (pp. 196. 28-200. 23 [Ziegler]).

8. Here ἐμβριθές is used as the opposite of λεπτομερές ( cf. Liddell and Scott, s.v. ἐμβρίθεια ii) as πυκνόν is of ἀραιόν.

9. 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.

10. cf. Cleomedes, ii. 5. 108 (p. 194. 20 ff. [Ziegler]).

11. Cleomedes, ii. 5. 109 (p. 198. 6-9 [Ziegler]).

12. 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.

Plutarch De Facie Quae in orbe Lunae Apparet 18

Harold Cherniss (Translator), William C. Helmbold (Translator)

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