Contents
Book I
[Meteors, Halo, Rainbow, Mock Sun, Etc.]
Preface
Contrast between human (moral) philosophy and divine (natural, physical). The sublime character of the latter which lifts us above the contemplation of the littlenesses of the earth and earthly life to the knowledge of God and His nature. Compared with astronomical conceptions and dimensions the world of man is but as a threshing-floor, the haunt of ants. The mind of man attains its true height in contemplation and investigation of these sublime facts. Some of the problems thus raised
Chap
I. Meteoric fires—she-goat, kid, etc. Occasions of their appearance; connection of portent with event. Explanation of the phenomena. They may be due to pressure of the atmosphere. Aristotle attributes them to the effect of terrestrial evaporation: difference of density causes various outbursts of this kind. They are analogous to lightning, but less violent
II. Halos. Produced by the light of a heavenly body striking the surrounding air and forming a circle as a stone does when thrown into a pond. Formed far away from the heavenly body and comparatively near the earth in the region of the wind. Require a particular state of the atmosphere neither too dense nor too thin. More frequent at night than day for this reason: by day the sun rarefies the air too much by its heat. Method of dissipation gives indication of wind or rain. Calmness a condition of formation, as in the analogous case of water
III. Rainbows. Generally by day, produced by inequalities of surface and density in clouds. Another species seen in a burst pipe or a fuller at work. Various explanations. Light and shade will not explain the varied colours. Some explain the rainbow as a confused reflection of the sun from individual drops of rain: every bounded surface, large or small, thus reflects—fish-pond and dew-drop equally. Aristotle attributes the confusion of colours to weakness of human sight; parallels may be found in persons whose sight is abnormally weak. As the innumerable drops, apparently without intervals, fall, human vision fails to distinguish severally the reflections of the sun, which thus become blended and confused. Vision is similarly deceived in the case of an oar in water, apples in a glass globe, etc., even in the size and movements of the sun himself. At any rate the rainbow requires both sun and cloud, and these opposite to each other. These two in operation produce the varieties of colour
IV. That the rainbow is an image is shown by the relation of sun to cloud in position, by the rapidity of formation and dispersion. Artemidorus’ explanation of the shape of the cloud (concave), and the consequent position of the red in the rainbow
V. Arguments to show that the cloud is coloured by the sun, like a dove’s neck or a peacock’s tail, and that the rainbow is not a reflection of the sun. The position (opposite) would be equally necessary in this case. Answer to this contention by Posidonius. The colour effects. Author agrees with Posidonius’ position but not his arguments. The only proof is the geometrical one
VI. Arguments from the size—never more than a semicircle—and shape of the bow. As the colour, whether real or reflected, is derived from the sun, so must also the shape be. The size is accounted for by the magnifying power of water, glass, etc. The sun as he appears in the rainbow is seen through moisture
VII. The arguments from the dispersion of the sun’s rays through glass (prism). Contention that they confirm author’s view 30
VIII. The form once more; why it is never larger than a semicircle. A wrong explanation refuted. Explanation of Aristotle’s remark as to the seasons of rainbows, in summer only in the morning or evening, in autumn at any time
XI. Mock suns. Their appearance and position in relation to the sun. They are a reflection of the sun in a suitable medium 34
XII. The formation of a mock sun may be compared to the image of the sun in eclipse as seen reflected in a dish of oil or pitch: the medium must be adapted to give the impression. The mock sun requires a certain consistency of cloud, failing which, a different effect is produced—obscuration, dissipation, etc.
XIII. There may be two mock suns simultaneously. Some think the one is a reflection of the other, the clouds acting as mirrors set opposite to one another. Mock suns, especially in the South, are a sign of rain
XIV. Other celestial fires. “Cave meteors,” “Barrel meteors,” “Chasms,” with a brief description of each. The rapidity of their flight, just as of lightning, deceives the sight. Their origin and cause. They indicate wind
XV. Gleams (flashes, σέλα). Their production and motions, varieties of them. Some do damage. Some are analogous to comets. “Bearded,” “torches,” “cypress” are different kinds. “Beams” and “barrels” may be of the same class. A curious case where such an appearance raised an alarm of fire. They are real fires. On the contrary, rainbows and halos are mere reflections. Mirrors have this wonderful power of false presentation
XVII. The philosophy of the looking-glass. The evolution of mirrors. Mirrors of full length are now used. They cost a fortune greater than the Senate gave Scipio’s daughters. A harmless necessary device has become an instrument of luxury, the adornment of women, the burden of men, nay, part of the kit of the soldier
Book II
[The Nature of Air. Thunder and Lightning]
[I.-XI. Prefatory to treatment of thunder and lightning, descriptive of the nature of the air, in which these phenomena occur.]
I. Divisions of physical science—astronomy, meteorology, geography. Cross divisions, e.g. earthquakes, belong to meteorology, being produced by air; so the earth, as a planet, belongs to Astronomy but its properties belong to Geography
II. Unity and composition in bodies. The analogy of the seen applies to the unseen. The atmosphere is possessed of unity (unitas) 52
III. Parts and material of bodies distinguished. In the human body blood is both 54
V. The earth is both part and material of the universe. From it nourishment is supplied to the latter 55
VI. The atmosphere has unity—is not compact of atoms, otherwise it could not exert tension, which is one of its main features, with endless manifestations
VII. There is no vacuum in the air, as the analogy of water shows 57
VIII. The exertion of tension presupposes tensibility, just as motion does mobility. Its existence in air proved by the effects of air, which tosses about mountains, houses, walls, etc. The propagation of sight and sound proves the same
IX. Its tension is seen in raising water, as in the jet in the amphitheatre. Proofs from a ship upborne of water, a quoit flung from a height, sound heard through a wall
X. Varieties of density and temperature in the atmosphere: the central layer is coldest 60
XI. The lower parts are most subject to change. The cause of this is in part the earth, in part the sun, moon, and other stars. So much by way of preface to explain the nature of that atmosphere in which thunder and lightning occur
XII. Lightning, thunder-bolt, thunder. All agree that they occur in the clouds, but different explanations are given of their cause and relations. Anaxagoras connects them with the ether; Aristotle says they are due to exhalations of various kinds, from the earth, coming in contact with the clouds
XIII. The fire cannot be inherent in the clouds and fall from them. When it so comes it is forced 64
XIV. There is nothing inconsistent with this in the explanation given (I. xv.) of meteors. There may be an analogy with what is observed in cases of fire when isolated groups of houses take fire through gradual accumulation of heat
XVII. Some explain the noise of thunder as due to hot meeting cold, as in the case of hot iron plunged into water 67
XVIII. Anaximander attributes the effects to air and explains all the phenomena by reference to it 67
XIX. Anaxagoras says it is the ether that acts on the lower atmosphere to produce them: it sends out fire 68
XX. Diogenes of Apollonia thinks that fire and air interact, producing one another, as may be observed in the various phenomena 68
XXI. Authorities discarded: independent explanation. A flash and a bolt are fire in some form: they differ only in degree 69
XXII. Analogy of fire on earth: it must apply above. Lightning due either to impact or friction. Hurricanes are a sufficient cause of the former
XXIII. Clouds and air may through friction also be a cause. The fires so produced are insubstantial and evanescent 71
XXIV. Fire by reason of its lightness levitates, just as water gravitates. But in the case of a bolt it is forced down, contrary to its nature, like a “weeping” tree
XXVI. There is no inconsistency in the combination in the same cloud of potential fire and water. A log burns at one end, exudes moisture at the other. An island on each of two occasions was thrown up by fire in the Aegean Sea, fire overcoming water. And clouds are, as a matter of fact, required for lightning: exceptions to this are only apparent
XXVIII. In order to the sound of thunder, clouds of a particular shape must meet in a particular way. A bladder does not burst with a report if cut. A broad simultaneous blow over the whole cloud is necessary to an explosion
XXIX. The proper shape and the rupture of the cloud are necessary. Compare drums, etc. 77
XXX. According to some, clouds are not necessary to thunder: witness eruptions of Etna and the overthrow of Cambyses’ army, where particles of sand were the medium of the thunder and lightning. But in this case, too, a cloud was formed, it may be, a denser, and more solid than one composed of mere air, before the sound was emitted
XXXIV. Mistaken views as to the relation of lightning to other presages. The former are of equal, not superior, value 82
XXXVI. “God is not a man” that he should change fate. What is the use, then, of rites? 84
XXXVII. Answer—Fate fixes some things only conditionally: the alternative issues are determined by the conduct, active or passive, of the worshipper 84
XXXVIII. This action of his is likewise a part of fate. The soothsayer, like the physician, is the minister of fate. Discussion of free will deferred
XXXIX. Three classes or kinds of thunderbolts, as judged by their indications, according to Caecina 86
XL. These are kinds of prognostications rather than of bolts. The different species of the latter are distinguished by their effects—boring, splitting, burning. Fine distinctions of Latin terms
XLI. A kind that stains or discolours. The Etruscan view of the three kinds of bolt according to their division 88
XLII. The Etruscans knew what they were about in attributing certain motives and actions to Jupiter. Their theory was for the benefit of the ignorant mass of humanity
XLIII. “Which things are an allegory.” An example is set to earthly rulers to be merciful and consider well their judgments 90
XLIV. Jove does not change his missiles; but there are gradations in the offence to be punished. That is the lesson 91
XLV. By Jove the Etruscans meant, as we do, all that is greatest and best—Fate, Providence, Nature, the Universe 91
XLVI. He is the source of the thunder’s power, though he does not superintend each stroke. Why he spares the guilty is another affair, which will be discussed in another place
XLVIII. It must be wrong, because the time is always limited. A better basis of treatment is that of Attalus. Place, time, person, etc., must all be looked into
LI. The signification of some does not affect, of some does not reach, us 95
LII. The force of lightning as seen in different materials, and at different times in the same material (cf. xxxi.) 96
LIV. Returns to Posidonius’ (Aristotle’s) opinion as to the cause of thunder, an explosion of air 98
LV. The collision of clouds may produce it. Air is the cause in this instance also. Shooting stars are associated with thunder, but this is the exception, not the rule
LVI. Heraclitus and Caecina think sheet lightning an intermittent incipient fire. Change in the pronunciation of the Latin word 100
LVII. Lightning is probably due to the air turning into fire through rarefaction of the clouds. It is naturally most frequent in summer. Sheet and forked lightning differ in degree, not in kind
LIX. Every story should have a moral. Death cannot be prevented; why fear it? It is cowardly and silly. Death by lightning is rather an honour than otherwise. Besides, fear is futile
Book III
On Forms of Water
Preface
Having begun a mighty task in my old age I must make up for lost time by hurrying on. The magnitude of it is actually an incentive to effort. Such studies are far superior to the historian’s task of recording the deeds of the robbers and butchers of mankind. The former raise us above the vicissitudes of fortune. “The principal thing” is to have a pure heart and clean hands, to escape slavery to self. The study of the universe exalts us to this
I. The cause of rivers and their varieties. Waters vary in amount at different seasons, in temperature, in medicinal qualities 114
III. Gravitation or the force of air determines the flow of water. Surface and spring water: they may be combined as in Lake Fucinus 115
IV. Why is the sea not filled nor the earth drained dry by rivers? 116
V. Some hold that what flows into the sea returns by secret passages cleansed of its salinity 116
VI. Some think rain supplies the rivers, and in proof cite the interior of Africa as contrasted with Gaul and Germany 117
VII. Objections to this argument. Rain does not penetrate more than 10 feet. If the earth is dry, it absorbs the rain; if it is saturated, the rain runs off. Again, rivers rise in rocks and mountains, where what rain ever fell must have run off. Rich wells of “living” water are found in the driest ground at depth. Fountains well out at mountain tops
VIII. The interior of the earth is, according to some, a huge receptacle of fresh water 118
IX. Others think the air which is contained within the earth being prevented from circulating turns into water 119
XII. The abundance of water is no difficulty, since it is a fourth part of the universe 123
XIII. The relation of water to the other elements. Thales’ silly notion that the earth sails in water like a ship at sea 124
XV. The veins of the earth resemble those of the human body. There are likewise the analogies of marrow, mucus, etc., of injuries and of bleeding, of parturition, perspiration, etc.
XVI. Intermittent fountains are an illustration of seasonal activity. The great vacant spaces of the earth and their tenants. Underground fish 128
XVII. The incredible wonders of nature are paralleled and even outdone by the excesses of luxury 129
XIX. To return—a sudden eruption of water casts up fish, generally poisonous. This points to the unfailing supply of subterranean water 132
XX. Various tastes of water due to four causes; qualities of water—petrifying, soporific, intoxicating, fatal 133
XXI. The same pestilential influence as taints rivers is perceived in caves: the noxious rivers flow from or through them 134
XXII. The Ocean and seas are coeval with the universe. So probably are abnormal rivers like the Danube and the Nile 135
XXV. Poisonous rivers. Colouring power of others. Great specific gravity of certain waters, its effects and cause 137
XXVI. Intermittent rivers and springs. Means possessed by river, fount, and sea of purifying themselves 141
XXVII. Digression on the universal deluge which will destroy the world. Nature is niggardly in creation, lavish in destruction. Ovid is unequal in his treatment of this catastrophe
XXVIII. Further imaginative pictures of what water can do by way of destruction. Alternative methods of destroying the earth—water and fire 148
XXIX. Further possibilities of the same character. Distinctions of seas, gulfs, etc., will all be obliterated; nature and the works of man will alike be overthrown
XXX. Nature shows by the chafing of the sea that she designs to inundate the world. A deluge is part of the fore-ordained plan. But there will be a new earth and a new race of men who will not sin—for a time
Book IV
CONTAINING A DISCUSSION OF SNOW, HAIL,
AND RAIN. [THE NILE]
Preface
The dangers of flattery and its insidiousness. If you must have praise, praise yourself. Lucilius has good cause: he must not, however, think too much of himself because he is governor of that historic province Sicily, which has ere now decided the fate of generals and of empire
I. Leaving Sicily and its marvels let us deal with the omitted part of the last book, the Nile. There is no real analogy between it and the Danube
II. The course of the Nile; its cataracts. The inundation of the river. Its meaning to Egypt. Its denizens; crocodiles and dolphins in conflict. Causes of the overflow: melting of snow; Etesian Winds; drying up of the springs through internal heat of the earth in winter; the attraction of the sun in Africa draws water from the sea to fill up the gap caused by evaporation [none of the accounts apparently accepted]
V. It is said that the cooler air of the North (Scythia, etc.) is stirred by the melting of the snow in spring and floats South, causing hail instead of rain
VI. Hail, it is again alleged, is averted by sacrifice. If there is not a victim handy you have merely to prick your finger! 181
VIII. Three causes why the air near the earth is warmest, and therefore produces snow rather than hail 182
XI. The tops of mountains, it is urged, should be warmer because nearer the sun. The difference is wholly inappreciable if we adopt the scale of the universe, the true one
XIII. The despicable luxury of the effeminate Romans, who bought snow, bathed in it, and must resort even to ice to cool the unnatural feverish thirst born of their indulgence
Book V
Treating of Winds and Movement of the Atmosphere
I. Definition of wind—air flowing in one direction. The air, like the sea, is always moving, even when it is thought to be still; hence the necessity of the additional qualification—in one direction
II. Democritus says wind arises from a multitude of atoms in a small space striving to get free, just like a crowd jostling each other
III. But wind does not thus depend on density; cloudy or misty weather does not necessarily produce wind, while wind is produced when the morning sun dissipates the air. Democritus is, therefore, wrong
IV. Wind arises in two ways—from the interior of the earth by emission—like wind on the stomach!—and from evaporation 196
V. The air has inherent power of movement, which is the chief cause of wind, evaporation being a less powerful one. Water has the power of moving and of imparting life to animals and plants
VI. Fire even, the destroyer, sometimes generates life. Air in like manner has a peculiar power of its own 197
IX. Connection of winds with seasons of the year and with the heat and light of the sun. The sun does not directly cause the winds
X. Some cite the Etesian Winds as proof that he does. They blow in summer when the snows melt and the moisture is carried South
XI. But as to the effect of the sun, there is no analogy between the Etesian Winds, which do not spring up till late in the day, and the winds which rise at dawn and fall as the day advances
XIII. The breaking up of clouds produces wind. Air, in an effort to get free, or heat, may produce this. Interruption of free passage may produce a whirlwind, just as an obstacle in a river a whirlpool. Violent whirlwinds take fire (πρηστήρ). Some winds produce different ones. An analogy holds between air and drops of moisture. A union of forces in air or in dew is necessary to give impulse and produce a current. Air and wind are merely a matter of degree
XV. Ancient miners of Philip’s saw rivers and vast underground reservoirs. It is some consolation to read such a story, which shows greed is no new vice: the older generations were as reckless as we are in their quest for treasure better hid
XVI. The four cardinal winds. The full list includes twelve. Their names and directions 208
XVII. The great circles of the earth which give twelve divisions, and therefore prescribe the possible number of the winds 210
XVIII. The uses of wind and the illustration afforded of the wisdom of Providence. The crops are dependent on it. So is commerce. But we make the sea a highway to war and not to peace. We go to seek for death, as if it were not always near. Xerxes, Alexander, Crassus are warnings of the mischievous use of power to cross the sea. Better, perhaps, the winds had never been given at all. But the value of a natural gift must not be estimated by the depraved use of it. Every gift, even sight and speech, man has perverted in the same way
Book VI
Treating of Earthquakes
CHAP. PAGE
I. Earthquake at Pompeii and the alarm it caused, many giving up Campania as a residence altogether. If the solid earth fail, what can be done? Refuge from tempest and fire and thunderstorm and war is possible, but not from earthquake. But (1) the whole earth is subject to such movement: we cannot escape by changing our ground—Tyre, Asia Minor, Achaia have all suffered. (2) Death is the same in whatever form it come, the circumstances matter not, a stone is all one with a mountain
II. We cannot escape death. The hopeless find refuge in despair. The knowledge of our frailty and mortality is our true solace. Death must come, a death with circumstance is rather to be preferred than otherwise. In an earthquake the earth shows itself mortal as men are
III. Our fears are due to ignorance. Through lack of a philosophic view of the universe we consider phenomena strange which are merely rare, e.g. eclipses. Fear may be removed by knowledge
IV. The study of such problems is the very worthiest; it reveals the secrets of nature, and is disinterested. But it is highly profitable at the same time
V. Various explanations of earthquakes have been suggested. The earlier ones are crude, but not therefore to be despised. Every subject develops as time goes on. Gratitude is due to the investigators who first dared to question nature
VI. The cause of earthquakes is by some said to be water. Thales of Miletus explains how this takes place, but he must be wrong: the analogy of a ship sailing the ocean will not apply to the earth (cp. III. xiii.)
VII. Water may be the cause, but may operate in quite different ways from those supposed by Thales. Storms, etc., in subterranean seas may cause earthquakes
VIII. There must be such subterranean water. The Tigris and Arethusa prove it. Nero, the virtuous and the veracious, sent two officers to investigate the sources of the Nile; their account confirms the assumption
IX. Fire is another alleged cause. It either bursts out through opposing obstacles, as in the clouds (Anaxagoras), or burns away the foundation and causes a subsidence at the spot
X. Pieces of the earth falling in merely through the decay of age may produce the effect without fire or any external influence. This is Anaximenes’ opinion
XI. Fire is supposed by some to cause earthquakes by expanding the vapour which it first causes to be given off from the subterranean waters
XII. Archelaus sets down the cause as air pressing up the earth’s internal wind which is already condensed to bursting point 239
XIII. Aristotle and Theophrastus take evaporation to be the cause. Strato, much in the same way, thinks that differences of internal temperature are the cause
XIV. By some it is thought that air is the cause, but that its operation, along with water, is like that of blood and air in the vessels of the body. The earth, it is assumed in this case, admits air, which must find an exit. When it does so violently, the result is an earthquake
XV. The earth is porous, perforated at many points, and it is thus that the air enters 243
XVI. The earth is full of air, nourishing plants rooted in it, and exhaling enough to feed the sun and the other heavenly bodies. Air is the most movable of elements; therefore the earth, if it is full of air, must also have frequent movements
XVII. Obstruction of air, just as of water, causes greater impetuosity when it escapes. Wind is frequently associated with earthquakes, as at Chalcis 245
XVIII. Additional considerations to prove that the great cause of earthquakes is air, i.e. wind 247
XIX. Metrodorus of Chios compares the rumbling of an earthquake to the resonance of the voice in a tub; the underground caves impart the sound
XX. Various combinations of water and air supposed by Democritus and Epicurus to co-operate to the production of earthquakes 249
XXIII. Next comes the form of concussion caused by air. The great Callisthenes, who braved the fury of Alexander and lost his life for it, supports this view. Submarine effects of it are particularly noticeable
XXIV. Different explanations may be given of the exact method in which air acts 255
XXV. The striving of the air in subterranean caverns produces a concussion or collapse in the earth above. The area of disturbance is limited, never over 200 miles, as numerous instances prove. The Peneüs and Ladon were thus produced
XXVI. The nature of the soil composed of muddy accretions without interstices is said to account for the exemption of Egypt from earthquakes. So Delos in the sea has porous rocks which emit the air easily. But the facts are wrong. There is abundant proof that proximity to the sea is no safeguard against shock
XXVII. A peculiarity of the Campanian earthquake, that it killed 600 sheep, is explained by the emission of pestilential vapour, by which sheep, with their heads close to the ground, naturally were most readily affected
XXVIII. Noxious vapours are not, however, peculiar to earthquakes. They are found in several parts of Italy habitually. Such, too, is the origin of new diseases
XXIX. Excessive fear drives people mad. Earthquakes split statues and divide kingdoms, e.g. Sicily from Italy, Spain from Africa 262
XXX. The action of the air accounts for all the detailed phenomena, splitting of walls, houses, towers, statues; also for the prolongation of shocks for several days
XXXI. A further proof that air is the agent is to be found in the gradually diminishing violence of the successive shocks. Phenomena in the pavement witnessed by a philosopher who was in his bath
XXXII. The moral. Life hangs on a thread; why should one dread the loss of it? The greatness of the cause of death is no source of terror. The hereafter is better and safer than earth. There there is no fear of earthquake or thunderstorm, fire or flood. Fear of death magnifies all human risks. Do not dread death, long for it, and, if necessary, meet it half way
Book VII
Treating of Comets
I. Phenomena, however wonderful, are not noted and admired unless they are uncommon. The sun and moon and starry heavens have no observers, but a Comet at once sets the whole world agog. The nature of the stars is a sublime and likewise a profitable study
II. The nature of Comets has not been hitherto fully investigated. They are so rare that one wants a record of the movements of all ever observed
III. Democritus, Eudoxus, Conon, Epigenes, and Apollonius of Myndus all fail to give any satisfactory account of the matter. Nor had the Egyptians or Chaldaeans investigated them
IV. Epigenes explains the Comet as due to a conjunction of Saturn with Mars or the Sun: it is akin to whirlwind and “beam” meteors
V. But there are essential differences between whirlwind, which is terrestrial, and beams and torches, which are above the clouds. There is a difference of duration also. Beams and Comets, it is true, have been mistaken for one another. It was a Comet, according to Aristotle, that appeared before the destruction of Buris and Helice. The character of the flame differs in the two forms
VI. There are two kinds of Comets, according to Epigenes. They are produced by air driven up and setting on fire suitable material above, which takes place every day at the same hour
VII. But Comets are not concomitants of winds; there is no parallelism in the phenomena. The higher ones, which have an orbit, he attributes to the north wind, but the facts do not square here either
X. The slowness and steadiness of the Comet could not be accounted for on this assumption, nor its general behaviour and shape 281
XI. We must look for some other explanation. Now Comets, it must be premised, appear in all quarters of the sky. Whatever the divisions of them made by the Greeks, they are all of one origin. Some of the ancients thought they were due to the union of two planets
XII. Again the facts do not square. Comets and planets appear simultaneously. A conjunction is momentary, a Comet lasts six months sometimes. The planets do not pass much beyond the ecliptic, but Comets appear in every quarter of the sky. And there are other objections
XIII. Artemidorus thinks the firmament is solid and has openings for stars. Comets are casual planets, or formed by conjunctions of them. His account is a tissue of barefaced falsehoods
XIV. How would a solid firmament be supported? No feasible explanation can be offered. Besides, the number of stars is so great—and they may all be “wanderers” if an indefinite number is—that there must be innumerable conjunctions of them, i.e. Comets. But, as a matter of fact, Comets are rare
XV. Again the huge Comets of the times of Demetrius and Attalus would require scores of planetary conjunctions to form them 288
XVI. Ephorus, a mere chronicler, who takes this view, has nothing to support him. He tries, like others of his set, to embellish his work by narrating marvels. Why did he not tell us what the two stars were into which the Comet resolved itself, as he alleges it did?
XVII. Apollonius of Myndus holds the Comet to be a true star (planet) with an erratic course, visible only when it approaches the lower part of its orbit. Different colours of Comets
XVIII. But Comets do not wax and wane as they approach and recede like planets. Nor do their orbits lie within the ecliptic. Besides, we can see through a Comet but not through a true star (planet)
XIX. Zeno the Stoic thinks the light of converging stars gives the appearance of a longer star. Others hold modified forms of the same opinion or analogous views
XX. Most of the Stoics hold Comets to be evanescent, and attribute them to friction of the air. Various phenomena are analogous 292
XXIV. There may be many stars in the universe whose paths have not been traced: Comets are such. No satisfactory explanation has been given of the mind, but its existence is not doubted
XXV. Comets are not yet fully understood. Many things are in the same category. A future age will be amazed at our ignorance of such matters
XXX. Humility is as becoming in investigators of the nature of the heavens as in worshippers. God has revealed but a little of Himself to man
XXXI. One cannot be surprised that everything has not yet been discovered. We must leave something to succeeding generations. We are not yet fully proficient in vice, though we have striven so long and hard. We still retain, strange to say, some traces of manhood
XXXII. We are all given up to low pleasures and vices, and devote our strength to them. Philosophy is kept for wet days. The old teachers have no successors. In fact, we are letting go what they discovered. We at best play with truth, which, as of old, lies at the bottom of the well, and needs the best efforts of young and old, late and early, to bring it to light