chidi cũ okguiva Sňom, nuì ráži rãiv áróμar Πολὺν Χρόνον, ἐτὶ ἐνίοτε συνχειμένη ὑπάρχει. | Saturn. 14. endeavours to overthrow this opinion of Epicurus. Ver. 156. That is to fay, the fmoothness of the mirror preferves the image. And here it will not be improper to obferve, that all men agree that two things are chiefly requifite in the nature of mirrors: Smoothnefs, which never is without plendour or fhining, and denfity of body: Nor an one of thefe fuffice without the other; for if the body be smooth and fhining, but of such a nature that the image may pafs through it, it will not be a mirror, nor reftore the images. Hence t is evident, that Plato in Timæus is mistaken, where he does not require denfity as neceffary in mirror, but only fplendour and smoothness. Now there are two opinions concerning the caufe f the reflection that is made by mirrors. Some old, that the images of the bodies placed against airrors are feen in them, not because the images thich we fee are in the glafs, but because the ght of the eyes, being darted upon the mirror in ftraight line, is reflected upon itself from the irror in another ftraight line. This was the opiion of the Pythagoreans, and is ftill of the maematicians. But others, of whom Epicurus feems > have been the first, will have the images to be apimitted from the bodies into the glafs, or any | her smooth and denfe body, and to be actually it; and that they are feen in the fame manner, ad for the fame reafon that all other things are, id are feen. But we fhall have occafion to fay tore of this by and by, when the poet comes to rgue particularly of mirrors. Ver. 163 For Lucretius believes with Epicurus ad Plato, that the image we regard in a mirror is t one conftant, fixed, certain, and fame thing, timige after image, ftill fucceeding in the place each other in an inftant of time, and without y interval or interruption. For Ver. 165. In thefe feven verfes he illuftrates, confirms the perpetual and never-cealing flux images, that all things may be full of light, rays u be continually emitted from the fan. e fame reafon, images likewife must be perpeally flying away from things; for which way ever you turn the mirror, the images of the opfite things appear; nor do they ever difappear long as thofe things keep their places. To confirm yet more this argumeat of Lucre25, we may add to the inftance he brings of the ans of the fun two other examples: I. The ime of a candle neither is, nor appears to be alays one and the fame flame, but only by reafon the never ceafing fubftitution of like and equilent little flames. II. A river is one and the me river, only because of the equivalence of the aters that are inceffantly fucceeding and driving ne another away. Hence it is, that the parts of image that proceed from hollow parts, are nore flowly caft upon the mirror, and reflected nore lowly likewife upon the eyes, than the parts gibbous and jut out. And, therefore, hough the image be feen imprinted on a flat bing, yet it makes an impreffion of a hollow or ound thing on the eye. But Macrobius, lib. vii. hat are Ver. 172. These ten verfes contain another ar. gument, but of lefs weight than the former. We fee the ferene unclouded fky often overcast on a fudden with thick and darkening clouds. But these clouds rife up from the earth, or from the fea; they are thick and heavy bodies: what then can ftop thin and light images? Ver. 180. This and the following verfes are repeated from above, ver. 125. as they are likewise in the original. Ver. 182. In these eight verses, Lucretius tells us, that he is going to dispute of the swiftnefs of these images; and that indeed there will be no need of a long difputation, fince mirrors demonftrate that images move with the greatest celerity that the mind of man can conceive. Ver. 188. These two verses in the original run thus: Parvus ut eft cycni melior canor; ille gruum Clamor in ætheriis difperfus nubibus austri. quam And we find them almost word for word in An- To what is already faid of the finging of fwans, Book II. ver. 479. and Book III. ver. 5. I will here add, that the ancient poets gave to one another the title of fwans. Virgil. Ecl. ix. ver. 27. Vare, tuum nomen Cantantes fublime ferens ad fidera cycni. i. e. "Poeta," according to Servius and all the annotators. Thus too Horace, Od. ii. lib. iv. ver. 25. Multa dircæum levat aura cycnum. that is, Pindar the Theban poct. Nor was it the poets only who believed the finging of fwans, for even Cicero tells us, that fwans are facred to Apollo, because they seem to have from him the gift of divination, inafmuch as forefeeing the good there is in death, they die finging, and with joy: "Cycni Apollini dicati funt, quod ab eo habere divinationem videantur; qui prævidentes quid in morte fit boni, cum cantu et voluptate moriuntur." Tufcul. 2. 73. Nevertheless, their finging is a mere fiction; and, indeed, both living and dying, they are mute, or at beft make only a harth unpleafing found: Therefore it is the more furprising, that there is fuch agreement of opinion among the Greeks and Latins concerning the melodious finging of fwans. Nazianzenus, Orat. 34 believes their finging to be only this, that when they fpread and clap their wings, the wind gets in, and whistles between their feathers. Of the cranes here mentioned by Lucretius, our tranflator takes no notice. The Latins called them grues, from the crunkling noife they make. They have a very long neck and beak, and are very common about the river Strymon in Macedonia on the confines of Thrace. They are said to forefee the ftormy weather, nay even a fhower of rain, and to fly from it in great numbers together. Hence Virgil Georg. i. ver. 374. | easily disengage and set themselves free: but heaf and light are emitted from the inward parts of the fun. Ver. 216. This and the following verfe are re Aut illum (fcil. imbrem) furgentem vallibus peated from Book ii. ver. 156. as well in the ori ginal as here. imis Aeria fugere grues. And for this reason Milton gives them the epithet, prudent: when speaking of birds, he says: Part loosely wing the region, part more wife, These are the birds that are faid to make war with the Pigmies; a people of Ethiopia, who inhabit the fens of the Nile, and exceed not three fpans in ftature, as Pliny witneffes. Of their wars with the cranes Juvenal pleasantly enough, Ad fubitas thracum volucres, nubemque fonoram; Sat. xiii. ver. 168. The fprawling warriors through the liquid air. Ver. 190. In these feventeen verfes, he explains the fwiftaefs of images, by making a comparifon between their motion and that of the rays of the fun, which reach from heaven to earth in an im perceptible space of time. But from whence proceeds this velocity of the fun-beams? They are fmall and fubtle bodies: They are easily emitted from the body of the fun: They are inceffantly in pursuit of one another, and therefore the following urges on the foregoing ray; and the interjacent air can be no hindrance to bodies of fo thin a texture. If thefe are the reafons that the rays of the fun move fo fwiftly, the fame reafons likewife will evince the extreme celerity of images. Ver. 193. This is taken from Cowley. See the note, Book ii. ver. 141. Ver. 204. That is, their fubtle nature; for an image, though it be corporeal, has not any dimenfion of profundity, but is all furface; as Epicurus fays in Laertius, lib. 10. Ver. 207. In the laft argument, he proved that images move as fwiftly as the rays of the fun; but now, in thefe eleven verfes, he makes them much swifter: for, fays he, the images are mere fubtle; and what conduces very much to their celerity, they Bow from the furface of things, and Ver. 218. In these ten verfes he calls experience to his affiftance. All fight is made by images: now, fet a mirror, or a bowel of water abroad in a clear night, and the images of all the stars will be reflected from the mirror or the water, and meet the eyes in a moment of time. Judge then, how fwift must be the paffage of those images. Ver. 219. Faber, in his note on this place, fays, that it is more furprifing to confider, how many different fpecies of itself water reflects all around, by its trembling motion; which Virgil describes in the following verses: Sicut aquæ tremulum labris ubi lumen ahenis, Which Dryden thus tranflates: Æn. viii. ver. 22 So when the fun by day, or moon by night, Strike on the polish'd glafs their trembling light; The glitt ring fpecies here and there divide, And caft their dubious beams from fide to fide: Now on the walls, now on the pavement play, And to the ceiling flash the glaring day. Ver. 226. This and the following verfe our tranflator has tranfcribed out of the first book of Cowley's Davideis. Ver. 228. But this flux or ftreaming of the images into the eyes, must be granted, fays the poet in these thirteen verfes, becaufe certain effluviums from other things infinuate themselves into all the other fenfes. Epicurus too made ufe of the fame argument, as Macrobius witneffes Lib. vii. Saturn. 14. in these words: "In propatulo eft quod decepit Epicurum à vero enim lapfus eft aliorum quatuor fenfuum fecutus exemplum: Quia in audiendo guftando, et odorando, atque tangendo nihil è nobis emittimus, fed extrinfecus accipimus quod fenfum moveat: Quippe et vox ad aures ultro venit, et auræ in nares influunt, et palato ingeritur quod gignit faporem, et corpori noftro applicantur tactu fentienda. Hinc putavit et ex oculis noftris nihil foras proficifci, fed imagines rerum ultro in oculis meare." It is manifeft what deceived Epicurus: for he was led into his error by following the example of the four other fenfes. And because, in hearing, smelling, tasting, and touching, we emit nothing out of ourselves, but receive from without what moves and affects the fenfe. Thus founds come to the ears of their own accord, and odours flow into the noftrils. Thus the tafie is produced by things that are received into the mouth; and whatever we perceive by touch is applied to the body. Hence he be lieved, that nothing goes out from the eyes, neither; but that the images of things come of their own accord into the eyes. Ver. 241. These ten verfes contain another argument. When we handle any thing in the dark, for example, a body that is quadrangular, how do we know it to be a square, but by its quadrangu- | lar figure? And if we place the fame body before our eyes in the light, how do we then know it to be a square, but by its quadrangular image? finaly in the dark as by day: That philofopher, Ver. 249. In these two verfes, Lucretius concludes, that images alone are the cause of fight: this too was the opinion of Epicurus, who held, that vifion is caufed by images that perpetually flow from things, and ftrike our eyes; and that this was his opinion, is affirmed by Aulus Gellius, in these words: "Epicurus autem affluere femper ex corporibus fimulacra quædam corporum ipfo rum, eaque fefe in oculos inferre, atque ita fieri fenfum videndi putat." Noct. Attic. lib. v. c. 16. Epicurus believed, that from all bodies fome images of thefe bodies are perpetually flowing; that they convey themselves into the eyes; and that thus is produced the sense of sight, And Macrobius, lib. vii. Sat. c. 14. fays the fame thing. "Cenfet Epicurus ab omnibus corporibus jugi❘ fluore quædam fimulacra manare, nec unquam tantulam moram intervenire, quin ultro ferantur inani figurâ cohærentes corporum Exuviæ quarum receptacula in noftris funt oculis, et ideo ad deputatam fibi à naturâ fedem proprii fenfus recurrunt." Epicurus believed that certain images are perpetually flowing from all bodies, and that without the leaft interval of time, the exuvia of bodies, composed of mere empty figures, are of their own accord conveyed to our eyes, which are their proper receptacles; and that therefore they are continually haftening to the proper feat of sense that nature has affigned them. Epicurus himself in Laertius, teaches, that these images izazivar And in Plutarch we find édéλwv dioxgious, the innuation of images, and in Cicero dúλwvuláressing the cause of fight. But the now uncontroThus we see what was the opinion of Epicurus concerning the cause of fight. But Plato held, that feeing is produced from the conjunction and affinity of two fires or lights; of one that goes out of our eyes, and of another that flows from the fun, or from the light. But the main difpute formerly was, whether vision be performed by the emiffion or reception of the rays of light. The mathematicians were perfuaded, that certain rays that ftream from the eyes, and reach to the object feen, enlighten and render it visible or apparent to the fight, and confequently are the cause of that fenfe. And this belief they ground.. ed on obfervations, that would by no means juflify their opinion; for they had taken notice that feveral animals which can fee by night, as cats, owls, &c. have eyes that sparkle in the dark; and from thence they inferred, that the light which is observed to be in their eyes, when it is night, is the cause they see, w en other creatures, whole eyes are not fo radiant, have no fight at all. But this opinion has been 10. face exploded: and Ariftotle retorted very well, that vifion cannot be performed by emiffion of the rays; becaufe in that cafe it would follow, that we fould have as clear a fight of things, and difcern them as diTRANS. II. | verted opinion is, that fight is formed by reception of the rays, and that the eye emits not any light to enlighten objects; but that vifion proceeds from the immiffion of the rays of light into the humours of the eye; and is formed by the rays proceeding from various points of a visible object; infomuch, that all the rays from one point of an object, are so inflected in the tunicles and humours of the eye, that they join again into one point at its bottom, and there paint the diftinct idea of the object but to show how it there causes fight would be too long a digreffion in this place. Ver. 251. In these fix verses, the poet farther teaches, that the images that are continually flowing from the furface of things, are prefent in all places, and standing all around us, fo that nothing hinders us to fee on their part, if we but turn our eyes, that are defigned for no other ufe than to fee them. Epicurus himself writes to the same purpose, in the epiftle to Herodotus: Añ dì xai νομίζειν ἐπεισίον]ος τινὸς ἀπὸ τῆ ἔξωθεν τὰς μορφὰς ορᾶν ἡμᾶς, καὶ διανοῦσθαι· ἰ γὰρ ἂν ἀποσφραγίσαι ο τὰ ἔξω τὴν ἑαυτῶν φύσιν τε τῆς χρώματος, καὶ τῆς μορφῆς, διὰ τῷ ἀέρος τῷ μεταξὺ ἡμῶν τῆς κακείνων 4ὸς διὰ τῶν ἀκε γίνων, ή δίων δήποτε ρευμάτων ἀφ ̓ ἡμῶν πρὸς ἐκεῖνα σας ραγινομένου ὅλοι, ὡς τύπων τινῶν ἐπεισιόντων ἡμῖν ἀπὸ I i τῶν πραγμάτων ομοχριώντε καὶ ὁμοιομόρφων κατὰ τὸ | the difference of thole colours : and we know for Ανάρμοστον μέγεθος εἰς τὴν ὄψιν ἢ τὴν διάνοιαν, ὠκέως τὸν φοραῖς χρωμένων. Ver 256. These are the very words Epicurus himself makes ufe of; and Lucretius after him believed, that an image is as it were a fhadow or type, which coming from the thing itself, brings with it the figure and colour of it; and which ftriking upon the eyes, exhibits and imprints in them the fame figure and colour. Thus Epicurus feems to have meant that impreffion and reprefentation of the image, which, by reason of the fmoothness of the eye, appears in the furface of it; and which may be feen in the pupil of any man's eye, if we look narrowly upon it. And this feems to have been the opinion of Democritus, as we find in Ariftotle, lib. de Senf. et Senf. cap 2. where Democritus faying rò ógāv divas î , that feeing is an apparition, Ariftotle blames him for it; and objects that that apparition is caufed only, Tò pμa lov, becaufe the eye is fmooth and glofly. Moreover, Lucretius himself, as we have seen in the third book, condemns their opinion, who, contrary to the doctrine of Epicurus, believe that the mind and foul fee from with. in through the eyes as through a window; and afferts, that it is not the mind, nor the foul, but the eyes themselves that fee, because they are endowed with foul, as well as all the other parts of the body. See book iii. ver. 130. et feq. Ver. 257. There are many problems, and those too very curious, concerning vilion. Some of these Lucretius propofes and explains. I. It is certain that we not only fee the colours and figures of things, but underftand, at the fame time, how far the objects feen are diftant from us: but how can the images that flow from the furface of things, be the cause of this? The poet answers in these ten verses. The image, ftriving to get to the eyes, drives forward all the air before it; now, this fream of air is longer or fhorter, as the object is more or lefs diftant. But the longer or shorter that ftream of air is, which, produced by the image, ftrikes the eye, fo much longer or fhorter the interval of fpace between the object and the eye must be allowed to be. But Lucretius and Epicurus are mistaken in this; for the dittance is not known by the eye, but by the fuperior faculty, the intellect, which compares and judges between the eye and the thing seen. We may judge of the diftanee of an object by the difpofition of the "axis vifionis:" for the foul, always attending to the various and different perceptions, eafily determines the length of the axis opticus," by the force it imparts to the fibres of the retina: infomuch that the colour of the object being first known, for the impreflions vary according to the difference of the colours, it is easily judged, that the body is more or lefs diftant. Thus, though a black body caufes not fo great an impreffion as a white, yet, if we look at a black ten yards from us, and at a white twenty, though the impreffion of this last be much the stronger, yet we judge the former to be the nearest to us, becaufe the foul firit difcerns between, and knows certain that men, who have been long accuftomed to judge of distances, are not so subject to miltake in that affair, as others who have had no experience therein; and the reafon of this is, because their fouls have formed a more perfect idea of the length of the optic axis, by means of the force it imparts. The particular difpofition of the eye conduces likewife very much to the forming a right judgment of the distance of objects: for we widen our eye when we are to regard an object diftant from us; and lengthen it when we look at one that is very near us; and, therefore, in all probable appearance, the eye is proportionably and gradually changed, as we view a nearer or more diftant object. For example, if I look at an object very near me, my eye is lengthened by the contraction of the oblique furrounding muf. cles: but if the fame object be carried by degrees farther off from me, thofe mufcles are gradually relaxed, proportionably as the object removes; and, at length, the right mufcles begin to widen the eye, the object drawing farther from it: this any man may obferve to be true, when he looks at a bird, for instance, first rising very near him, and then flying from him by degrees, till at length it arrive at a great diftance from him. Some attribute this appearance to the knowledge of the conjunction of the two " axes vifionis," which may indeed be fome help towards the diftinguishing the distance of objects; and this is the realon why we cannot fo well judge of the distance of an object, when we regard it only with one eye, as when we look on it with both. Moreover, the farther diftant an object is from us, the more fubject we are to be deceived in our judgment of its diftance, as any man will readily conceive. Ver. 267. In thefe twelve verfes is contained the fecond problem. Why, fince the objects themfelves are seen, the images that strike the eyes one by one, and are the caufe of our feeing them, can be feen themfelves? To this Lucretius an fwers, after his ufual manner, by bringing like inftances. 1. We feel not the fingle parts of wind or of cold but of all the wind, or all the cold, we are very fenfible. 2. When we touch with our fingers the furface, or outmost colour of a ftone, we feel not that furface and outmost colour; but only the interior hardness of the stone. Now, fuppofe the images to be as the fingle parts of the wind and cold, and the objects themselves to be as the whole wind and cold, and this difficulty is eafily folved. In like manner, fuppofe the ftone to be as the object, and the furface and outmoft colour of it as the image. Thus atoms, the wind, and images are invisible themselves, though visible things are made of them, and though by their means other things are feen. Ver. 277. He means what Lucretius here calls "Summum colorem," the utmost colour. For even by the doctrine of Lucretius, colour cannot be touched. Ver. 279. Third problem. Why the images of things reflected from the surface of a glafs mirror, are not feen in that furface, but as it were within, or beyond it? The reason of this the poet gives us in these twenty-one verses. The eye knows the distance of the thing feen, by means of the air that is driven by the image to the eye. Now, when two airs are driven, the interval must of neceffity be more extended, and even doubled. But the image of the glafs (for we fee the glafs itfelf as well as the thing, whofe image is reflected) protrudes one air, and the image reflected another. And this is the reafon why the image appears to be not in the surface of the glass, but as if it were within and beyond it. He alfo illuftrates this explication, by bringing an example of things that are seen in a straight line, and at a distance fron a place within a building: in which case the images drive the air forward, as well through the space without doors to the very threshold, as through the space within doors from the threshold to the very eye. This reafon, though it seems probable, is nevertheless not true; for as I faid before, it belongs not to the eyes, but to the fuperior faculty, to difcern and judge of diftance. Lucretius here affords us an opportunity to give a fhort account of the looking-glaffes that are most common among us, and of which there are three forts: viz. The plain, the concave, and the convex. The furface of the plain is an exac level, and these are the most general, and efteemed the best, because they reflect the object exactly the fame, in fite, diftance, and magnitude, as it is reprefented to them. But the other two forts, the concave and the convex, return the objects differing now in fite, now in diftance, now in magnitude, according to the fite of the objects, and as the eye receives the reflection. Plain glaf fes, as I faid before, caufe no alteration either in the fite, distance, or magnitude of the objects they represent The reason of which is, because, being fmooth and level, they give no other modifications to the rays, but only that of fimple reflection, according as they fall on it. Firft. As to the fite, it will be reprefented the fame as it is out of the glass; that is to fay, in the fame line of attitude; and the object feems fo much beyond the glafs as it is on this fide, because the rays reflected from the glass, run the fame lines, and make the fame impreffion on the retina, as they would do if the object were really on that fide where it is reprefented: for the fite of an object is diftinguished by the impulse of the rays from a determinate region. Secondly, In regard to the diftance, the object is reprefented as far beyond the glafs as it is on this fide of it, because the impreflion of the rays is altogether as ftrong after as before the reflection. For a clearer idea of this, fee the note on ver. 257. where we have treated of the manner how to judge the true distance of an object from the eye. Thirdly, We fee the magnitude of an object exactly the fame as it really is, because the line of reflection from the glafs being exactly equal with that of incidence from the object, the rays from the remoter points of the object will be as far diftant from each other then, as they would be if the very object itfelf were really in the place where it is only reprefented. Nor, in deed, can we err in the magnitude, so long as we are right in our judgment concerning the distance of the object. But before I close this note, I must not forget to observe, that our tranflator has omitted the three last verses of this argument, which in Lucre. tius runs thus: Quare etiam atque etiam minime mirarier eft par Illis, quæ reddunt fpeculorum ex æquore vifum. Aeribus binis, quoniam res confit utroque. Lambinus abfolutely rejects this; and Creech, in his Latin edition fays, that he fees no caufe why he need ever be ashamed of, or revoke that cenfure: because the verses are altogether useless, and have nothing to do in this place: and for that reason I have avoided to give them in this transla tion. Ver. 290. Not the image that is emitted from the object placed before the glass, and that strikes into the glass; but the image that flows from the glafs itfelf: for all things emit images, even mirrors themselves. Ver. 299. For the image appears as far beyond the glass, as the object of which it is the image is diftant from the glass. Ver. 300. It is repugnant to the foregoing opinion of Epicurus, that the image in the glafs should be turned towards the person whofe image it is, and look back upon him. For, fince the image flows from us, and goes ftraight forward, it ought, as it goes away, to fhow us its hinder parts, fo that the right may answer to the right, and the left to the left. In like manner, as a player, when his mask is taken off, regards that part of it which he wore next him, that is to fay, not the face, but the hollow behind it. To this purpose Macrobius, who, by this argument, endeavours to overthrow the opinion of Epicurus, that the images of things come into our eyes of their own accord. His words, fpeaking of that belief, are thefe: "Cujus opinioni repugnat, quod in fpeculis imago adverfa contemplatorem fuum, refpicit: cum debeat, fiquidem à nobis orta recto meatu proficifcitur, pofteram fui partem, cum difcedit, oftendere, ut læva lævam, dextera dexteram refpiciat: Nam et hiftrio perfonam fibi detractum ex eâ parte videt, quâ induit; fcilicet non faciem, fed pofteriorem cavernam." Saturnal. lib. vii. cap. 14 This, therefore, is the fourth problem: and to folve the difficulty of it, Lucretius defends his opinion by the example which his adverfaries allege to weaken it. fake, fays he, a form or mask made of clay, not hardened; but while it is yet moist, and dash it against a beam or pillar, fo as to invert it backwards, that the face may fill up the hollow; and you will then fee that brought to pass in the mask, which you are now astonish. ed to fee in the mirror. And, therefore, you ought not to doubt in the leaft, but that images, being, as they are, very tenuious fubftances, may, by dashing against the glass, be inverted back. wards in like manner. For an image has no depth, nor profundity whateve This folution of this problem agrees not ill, but is almost the |