Plutarch, De Facie Quae in orbe Lunae Apparet, Harold Cherniss (Translator), William C. Helmbold (Translator), 23

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[23] There is this, however, I said, which seems to be a stronger objection to the alleged reflection from the moon. It happens that those who have placed themselves in the path of reflected rays see not only the object illuminated but also what illuminates it. For example, if when a ray of light rebounds from water to a wall the eye is situated in the place that is itself illuminated by the reflection, the eye discerns all three things, the reflected ray and the water that causes the reflection and the sun itself,¹ the source of the light which has been reflected by impinging upon the water. On the basis of these admitted and apparent facts those who maintain that the moon illuminates the earth with reflected light are bidden (by their adversaries)² to point out in the moon at night an appearance of the sun such as there is in water by day whenever there is a reflection of the sun from it. Since there is no such appearance, (these adversaries) think that the illumination comes about in another way and not by reflection and that, if there is not reflection, neither is the moon an earth. What response must be made to them then? said Apollonides, for the characteristics of reflection seem to present us with a problem in common.³ In common in a way certainly, said I, but in another way not in common either. In the first place consider the matter of the image,⁴ how topsy-turvy and like rivers flowing uphill⁵ they conceive it. The fact is that the water is on earth and below, and the moon above the earth and on high; and hence the angles produced by the reflected rays are the converse of each other, the one having its apex above at the moon, the other below at the earth.⁶ So they must not demand that every kind of mirror or a mirror at every distance produce a similar reflection, since (in doing so) they are at variance with the manifest facts. Those, on the other hand, who declare that the moon is not a tenuous or a smooth body as water is but a heavy and earthy one,⁷ I do not understand why it is required of them that the sun be manifest to vision in her. For milk does not return such mirrorings either or produce reflections of the visual ray, and the reason is the irregularity and roughness of its particles⁸; how in the world the is it possible for the moon to cast the visual ray back from herself in the way that the smoother mirrors do? Yet even these, of course, are occluded if a scratch or speck of dirt or roughness covers the point from which the visual ray is naturally reflected, and while the mirrors themselves are seen they do not return the customary reflection.⁹ One who demands that the moon either reflect our vision from herself to the sun as well or else not reflect the sun from herself to us either is naive, for he is demanding that the eye be a sun, the vision light, and the human being a heaven. Since the light of the sun because of its intensity and brilliance arrives at the moon with a shock, it is reasonable that its reflection should reach to us; but the visual ray, since it is weak and tenuous and many times slighter, what wonder if it does not have an impact that produces recoil or if in rebounding it does not maintain its continuity but is dispersed and exhausted, not having light enough to keep it from being scattered about the irregularities and corrugations (of the moon)? From water, to be sure, and from mirrors of other kinds it is not impossible for the reflection (of the visual ray) to rebound to the sun, since it is still strong because it is near to its point of origin¹⁰; but from the moon, even if the visual rays do in some cases glance off, they will be weak and dim and prematurely exhausted because of the magnitude of the distance.¹¹ What is more too, whereas mirrors that are concave make the ray of light more intense after reflection than it was before so as often even to send off flames,¹² convex and spherical mirrors¹³ by not exerting counterpressure upon it from all points [give it off] weak and faint. You observe, I presume, whenever two rainbows appear, as one cloud encloses another, that the encompassing rainbow produces colours that are faint and indistinct. The reason for this is that the outer cloud, being situated further off from the eye, returns a reflection that is not intense or strong.¹⁴ Nay, what need of further arguments? When the light of the sun by being reflected from the moon loses all its heat¹⁵ and of its brilliance there barely reaches us a slight and feeble remnant, is it really possible that of the visual ray travelling the same double-course¹⁶ any fraction of a remnant should from the moon arrive at the sun? For my part, I think not; and do you too, I said, consider this. If the visual ray were affected in the same way by water and by the moon, the full moon ought to show such reflections of the earth and plants and human beings and stars as all other mirrors do; but, if there occur no reflections of the visual ray to these objects either because of the weakness of the ray or the ruggedness of the moon, let us not require that there be such reflection to the sun either.

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

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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.) — 23 focus

[23] ἀλλʼ ἐκεῖνο μᾶλλον ἔφην ἐλέγχειν δοκεῖ τὴν λεγομένην ἀνάκλασιν ἀπὸ τῆς σελήνης, ὅτι τοὺς ἐν ταῖς ἀνακλωμέναις αὐγαῖς ἑστῶτας οὐ μόνον συμβαίνει 10 τὸ φωτιζόμενον ὁρᾶν, ἀλλὰ καὶ τὸ φωτίζον. ὅταν γάρ, αὐγῆς ἀφʼ ὕδατος πρὸς τοῖχον ἁλλομένης, 936c ὄψις ἐν αὐτῷ τῷ πεφωτισμένῳ κατὰ τὴν ἀνάκλασιν τόπῳ γένηται, τὰ τρία καθορᾷ, τὴν τʼ ἀνακλωμένην αὐγὴν καὶ τὸ ποιοῦν ὕδωρ τὴν ἀνάκλασιν καὶ τὸν 15 ἣλιον αὐτόν, ἀφʼ οὗ τὸ φῶς τῷ ὕδατι προσπίπτον ἀνακέκλασται. τούτων δʼ ὁμολογουμένων καὶ φαινομένων, κελεύουσι τοὺς ἀνακλάσει φωτίζεσθαι τὴν γῆν ὑπὸ τῆς σελήνης ἀξιοῦντας ἐπιδεικνύναι νύκτωρ ἐμφαινόμενον τῇ σελήνῃ τὸν ἥλιον, ὥσπερ 20 ἐμφαίνεται τῷ ὕδατι μεθʼ ἡμέραν, ὅταν ἀνάκλασις ἀπʼ αὐτοῦ γένηται· μὴ φαινομένου δὲ τούτου, κατʼ 936d ἄλλον οἴονται τρόπον, οὐκ ἀνακλάσει, γίγνεσθαι τὸν φωτισμόν· εἰ δὲ μὴ τοῦτο, μηδὲ γῆν εἶναι τὴν σελήνην. τί οὖν ἔφη πρὸς αὐτοὺς λεκτέον ὁ Ἀπολλωνίδης; 25 κοινὰ γὰρ ἔοικε καὶ πρὸς ἡμᾶς εἶναι τὰ τῆς ἀνακλάσεως. ἀμέλει τρόπον τινά ἔφην ἐγώ κοινά, τρόπον δʼ ἄλλον οὐδὲ κοινά· πρῶτον δʼ ὅρα τὰ τῆς εἰκόνος ὡς ἄνω ποταμῶν καὶ τραπέμπαλιν λαμβάνουσιν. ἐπὶ γῆς γάρ ἐστι καὶ κάτω τὸ ὕδωρ, ὑπὲρ γῆς δὲ σελήνη καὶ μετέωρος ὅθεν ἀντίστροφον αἱ κεκλασμέναι τὸ σχῆμα τῆς γωνίας ποιοῦσι, τῆς 5 μὲν ἄνω πρὸς τῇ σελήνῃ τῆς δὲ κάτω πρὸς τῇ γῇ τὴν κορυφὴν ἐχούσης· μὴ ἅπασαν οὖν ἰδέαν κατόπτρων μηδʼ ἐκ πάσης ἀποστάσεως ὁμοίαν ἀνάκλασιν 936e ποιεῖν ἀξιούτωσαν, ἐπεὶ μάχονται πρὸς τὴν ἐνάργειαν. οἱ δὲ σῶμα μὴ λεπτὸν μηδὲ λεῖον, 10 ὥσπερ ἐστὶ τὸ ὕδωρ, ἀποφαίνοντες τὴν σελήνην, ἀλλʼ ἐμβριθὲς καὶ γεῶδες, οὐκ οἶδʼ ὅπως ἀπαιτοῦνται τοῦ ἡλίου τὴν ἔμφασιν ἐν αὐτῇ πρὸς τὴν ὄψιν οὐδὲ γὰρ τὸ γάλα τοὺς τοιούτους ἐσοπτρισμοὺς ἀποδίδωσιν οὐδὲ ποιεῖ τῆς ὄψεως ἀνακλάσεις 15 διὰ τὴν ἀνωμαλίαν καὶ τραχύτητα τῶν μορίων· πόθεν γε τὴν σελήνην δυνατόν ἐστιν ἀναπέμπειν 936f ἀφʼ ἑαυτῆς τὴν ὄψιν, ὥσπερ ἀναπέμπει τὰ λειότερα τῶν ἐσόπτρων; καίτοι καὶ ταῦτα δήπουθεν, ἐὰν ἀμυχή τις ἢ ῥύπος ἢ τραχύτης καταλάβῃ τὸ σημεῖον, 20 ἀφʼ οὗ πέφυκεν ἡ ὄψις ἀνακλᾶσθαι, τυφλοῦται καὶ βλέπεται μὲν αὐτά, τὴν δʼ ἀνταύγειαν οὐκ ἀποδίδωσιν. ὁ δʼ ἀξιῶν ἢ καὶ τὴν ὄψιν ἡμῶν ἐπὶ τὸν ἥλιον ἢ μηδὲ τὸν ἥλιον ἐφʼ ἡμᾶς ἀνακλᾶν ἀφʼ ἑαυτῆς τὴν σελήνην ἡδύς ἐστι. τὸν ὀφθαλμὸν ἥλιον 25 ἀξιῶν εἶναι φῶς δὲ τὴν ὄψιν οὐρανὸν δὲ τὸν ἄνθρωπον. τοῦ μὲν γὰρ ἡλίου διʼ εὐτονίαν καὶ λαμπρότητα πρὸς τῇ σελήνῃ γιγνομένην μετὰ πληγῆς τὴν ἀνάκλασιν φέρεσθαι πρὸς ἡμᾶς εἰκός ἐστιν· ἡ δʼ ὄψις ἀσθενὴς οὖσα καὶ λεπτὴ καὶ ὀλιγοστή, τί θαυμαστὸν 5 εἰ μήτε πληγὴν ἀνακρουστικὴν ποιεῖ μήτʼ ἀφαλλομένη τηρεῖ τὴν συνέχειαν ἀλλὰ θρύπτεται 937a καὶ ἀπολείπει, πλῆθος οὐκ ἔχουσα φωτὸς ὥστε μὴ διασπᾶσθαι περὶ τὰς ἀνωμαλίας καὶ τραχύτητας; ἀπὸ μὲν γὰρ ὕδατος καὶ τῶν ἄλλων ἐσόπτρων ἰσχύουσαν 10 ἔτι τῆς ἀρχῆς ἐγγὺς οὖσαν ἐπὶ τὸν ἥλιον ἅλλεσθαι τὴν ἀνάκλασιν οὐκ ἀδύνατόν ἐστιν· ἀπὸ δὲ τῆς σελήνης, κἂν γίγνωνταί τινες ὀλισθήσεις αὐτῆς, ἀσθενεῖς ἔσονται καὶ ἀμυδραὶ καὶ προαπολείπουσαι διὰ τὸ μῆκος τῆς ἀποστάσεως, καὶ γὰρ ἄλλως τὰ 15 μὲν κοῖλα τῶν ἐσόπτρων εὐτονωτέραν ποιεῖ τῆς προηγουμένης αὐγῆς τὴν ἀνακλωμένην, ὥστε καὶ 937b φλόγας ἀναπέμπειν πολλάκις· τὰ δὲ κυρτὰ καὶ τὰ σφαιροειδῆ τῷ μὴ πανταχόθεν ἀντερείδειν ἀσθενῆ καὶ ἀμαυράν. ὁρᾶτε δήπουθεν, ὅταν ἴριδες δύο 20 φανῶσι, νέφους νέφος ἐμπεριέχοντος, ἀμαυράν ποιοῦσαν καὶ ἀσαφῆ τὰ χρώματα τὴν περιέχουσαν τὸ γὰρ ἐκτὸς νέφος ἀπωτέρω τῆς ὄψεως κείμενον οὐκ εὔτονον οὐδʼ ἰσχυρὰν τὴν ἀνάκλασιν ἀποδίδωσι. καὶ τί δεῖ πλείονα λέγειν; ὅπου γὰρ τὸ τοῦ ἡλίου 25 φῶς ἀνακλώμενον ἀπὸ τῆς σελήνης τὴν μὲν θερμότητα πᾶσαν ἀποβάλλει, τῆς δὲ λαμπρότητος αὐτοῦ λεπτὸν ἀφικνεῖται μόλις πρὸς ἡμᾶς καὶ ἀδρανὲς λείψανον· ἦπου τῆς ὄψεως τὸν ἴσον φερομένης δίαυλον ἐνδέχεται μόριον ὁτιοῦν λείψανον ἐξικέσθαι 937c πρὸς τὸν ἣλιον ἀπὸ τῆς σελήνης; ἐγὼ μὲν οὐκ 5 οἶμαι. σκοπεῖτε δʼ εἶπον καὶ ὑμεῖς· εἰ ταὐτὰ πρὸς τὸ ὕδωρ καὶ τὴν σελήνην ἔπασχεν ἡ ὄψις, ἔδει καὶ γῆς καὶ φυτῶν καὶ ἀνθρώπων καὶ ἄστρων ἐμφάσεις ποιεῖν τὴν πανσέληνον, οἵας τὰ λοιπὰ ποιεῖται τῶν ἐσόπτρων· εἰ δʼ οὐ γίγνονται πρὸς ταῦτα τῆς ὄψεως 10 ἀνακλάσεις διʼ ἀσθένειαν αὐτῆς ἢ τραχύτητα τῆς σελήνης, μηδὲ πρὸς τὸν ἣλιον ἀπαιτῶμεν.

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.) — 23 focus

[23] But this, said I, seems rather to refute and check the reflection and reverberation which is said to rebound from the moon; because those who are within retorted rays do not only see that which is enlightened, but also that which enlightens. For when, at the resulting of light from water upon a wall, the sight falls upon the place which is thus illuminated by the reflection, the eye there beholds three things, to wit, the ray or light that is driven back, the water which makes the reflection, and the sun himself, whose light, falling on the superficies of the water, is repulsed and sent back. This being confessed, as what is evidently seen, it is required of those who say that the earth is enlightened from the moon by the reflections of the sun’s rays upon it, that they show us by night the sun appearing upon the superficies of the moon, in the same manner as he may be seen by day appearing in the water on which he shines when there is the said reflection of his beams. But since the sun does not so appear, they thence infer that the moon receives her illumination by some other means, and not by reflection; and if there is no reflection, the moon then is not earth.

What answer then is to be made them, said Apollonides? For the argument of this objection against reflection is common also to us.

It is indeed, answered I, in some sort common, and in some sort not. But first consider the comparison, how perversely and against the stream they take it. For the water is here below on the earth, and the moon there above in heaven. So that the reflected and reverberated rays make the form of their angles quite opposite one to the other, the one having their point upwards towards the superficies of the moon, and the other downwards toward the earth. Let them not then require that from every form of mirror, nor that from every distance and remoteness, there should be a like and semblable reflection; for so doing, they would repugn notorious and apparent evidence. And as for those who hold the moon to be a body not smooth, even, and subtile as the water, but solid, massy, and terrestrial, I cannot conceive why they should require to see the image of the sun in her as in a glass. For neither does mill itself render such peculiar images, nor cause reflection of the sight, by reason of the inequality and ruggedness of its parts. How then is it possible that the moon should send back the sight from her superficies, as mirrors do that are more polished? And if in these also there is any scratch, filth, or dulness on their superficies whence the reflected sight is wont to receive a form, they are dimmed, and although the mirrors may be seen, they yield no counterlight. He then who requires that either the sun should appear in the moon, or else the moon should not reflect the sun’s light to us, might as well require that the eye be the sun, the sight light, and man heaven. For it is probable, that the reflection of the sun’s beams which is made upon the moon does, by reason of their vehemence and great brightness, rebound with a stroke upon us. But our sight being weak and slender, what wonder is it, if it neither give such a stroke as may rebound, or if it rebounds, that it does not maintain its continuity, but is broken and fails, as not having such abundance of light that it should not disgregate and be dissipated within those inequalities and asperities? For it is not impossible, that the reflection upon water or other sorts of mirrors, being yet strong, powerful, and near its origin, should from thence return upon the eye; but though there may perhaps from the moon be some glimmerings, yet they still will be weak and obscure, and will fail in the way, by reason of so long a distance. For otherwise hollow and concave mirrors send back the reverberated and reflected rays stronger than they came, so that they frequently burn and set on fire; and those that are convex and embossed like a bowl, because they beat them not back on all sides, render them dark and feeble. You see for certain, when two rainbows appear together in the heaven, one cloud comprehending another, that the rainbow which outwardly environs the other yields dim colors, and such as are not sufficiently distinguished and expressed, because the exterior cloud, being more remote, makes not a strong and forcible reflection. And what needs there any more to be said, seeing that the very light of the sun, reverberated and sent back by the moon, loses all its heat; and of his brightness, there comes to us with much ado but a small remainder, and that very languishing and weak? Is it then possible, that our sight, turning the same course, should bring back any part of the solar image from the moon? I for my part think it is not. But consider, I said, yourselves, that if our sight were in one and the same manner affected and disposed towards the water and towards the moon, the full moon would of necessity represent to us the images of the earth, plants, men, and stars, as is done by the water and all other sorts of mirrors. And if there is no such reflection of our sight as to bring us back these images, either by reason of our said sight’s weakness, or through the rugged inequality of the moon’s superficies, let us no longer require that it should rebound against the sun.

Notes on the current edition

Concerning the Face which Appears in the Orb Of the Moon

1. i.e. the image of the sun in the water or the reflecting surface.

2. i.e. by the Stoics; cf. e.g. the argument of Cleomedes (ii. 4. 101-102 [p. 184. 4 ff., Ziegler]) against the explanation of the moon’s light as reflection. The following argument in this passage is printed by von Arnim, S. V. F. ii, p. 199 as frag. 675 of Chrysippus.

3. For the idiom, κοινὸν καὶ πρός τινα εἶναι, cf. Lucullus, 44 (521 A) and 45 (522 B). Apollonides is a geometer ( cf. 920 F and 925 A-B supra) who had expressed admiration for Clearchuss theory of reflection from the moon ( cf. 921 B supra); by καὶ πρὸς ἡμᾶς here he means that the objection just raised to reflection from the moon constitutes a difficulty for the theory which he has espoused as well as for that of Lamprias and Lucius which he has just attacked. Lamprias in his reply, however, contends that the physical characteristics of the moon on his theory, the very characteristics to which Apollonides has just objected (935 D-E), will explain why the objection does not really make the difficulty for his theory that it would for that of Clearchus.

4. i.e. the reflected image, not the simile, as Amyot and Prickard interpret it.

5. For the proverbial expression cf. Hesychius, s. v. ἄνω ποταμῶν; Euripides, Medea, 410 ; Lucian, Dialogi Mortuorum, 6. 2.

6. As Kepler says in his note 64 ad loc., ratio nihil ad rem.

7. i.e. those who hold the view of the moon’s nature that Lamprias himself espouses.

8. cf. Quaest. Conviv 696 A; and observe that the phrase, ἀνωμαλία καὶ τραχύτης, used here of milk is in 930 D supra and 937 A s.v. applied to the moon.

9. For the phenomenon referred to cf. [Ptolemy], Speculis, vi = Hero Alexandrinus, Opera, ii. 1, p. 330. 4-22 (Nix-Schmidt). For τυφλόω meaning to deaden, muffle, occlude cf. Defectu Oraculorum, 434 c, Quaest. Conviv 721 B, Esu Carnium, 995 f.

10. Plutarch has to explain how the image of the sun can be seen in water and mirrors though it is not seen in the moon, and he does so by stressing the proximity of the former to the point of origin. This point of origin can only be our eyes, so that he must be thinking of the visual ray as reflected from water and mirrors to the sun and as failing to be reflected from the moon to the sun. The reading of the mss., ἐπὶ τὸν ἥλιον, is necessary to the argument and all suggestions for altering it are wrong.

11. i.e. the distance from the eye to the reflecting surface of the moon.

12. For the concave burning-glass cf. [Euclid], Catoptrica Prop. 30 (Euclid, Opera Omnia, vii, pp. 340-342 [Heiberg]) 154.

13. Not two kinds of mirrors, as Raingeard says ad. loc., but one, convex, i.e. convex spherical, for (1) spherical mirrors that are concave are the burning-glasses in the preceding category, and (2) convex mirrors that are not spherical would not provide the obvious analogy with the moon that is wanted.

14. On the double rainbow and the reason why the outer bow is less distinct cf. Aristotle, Meteorology, 375 A 30-b 15. Aristotle’s explanation, which Plutarch here adopts, is attacked by Kepler in a long note on the present passage (note 70).

15. See note a on 929 E supra.

16. The moon is thought of as the καμπτήρ or turning-post in the stadium. The sun’s rays travel from sun to moon to eye, and the visual ray would have to travel the same course in reverse.

Plutarch De Facie Quae in orbe Lunae Apparet 23

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

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