Consolations in Travel Part 5

DIALOGUE THE SIXTH. POLA, OR TIME.

During our stay in Illyria, I made an excursion by water with the Unknown, my preserver, now become my friend, and Eubathes, to Pola, in Istria. We entered the harbour of Pola in a felucca when the sun was setting; and I know no scene more splendid than the amphitheatre seen from the sea in this light. It appears not as a building in ruins, but like a newly erected work, and the reflection of the colours of its brilliant marble and beautiful forms seen upon the calm surface of the waters gave to it a double effect--that of a glorious production of art and of a magnificent picture. We examined with pleasure the remains of the arch of Augustus and the temple, very perfect monuments of imperial grandeur. But the splendid exterior of the amphitheatre was not in harmony with the bare and naked walls of the interior; there were none of those durable and grand seats of marble, such as adorn the amphitheatre of Verona, from which it is probable that the whole of the arena and conveniences for the spectators had been constructed of wood. Their total disappearance led us to reflect upon the causes of the destruction of so many of the works of the older nations. I said, in our metaphysical abstractions, we refer the changes, the destruction of material forms, to time, but there must be physical laws in Nature by which they are produced; and I begged our new friend to give us some ideas on this subject in his character of chemical philosopher. If human science, I said, has discovered the principle of the decay of things, it is possible that human art may supply means of conservation, and bestow immortality on some of the works which appear destined by their perfection for future ages.

_The Unknown_.--I shall willingly communicate to you my views of the operation of time, philosophically considered. A great philosopher has said, man can in no other way command Nature but in obeying her laws; and, in these laws, the principle of change is a principle of life; without decay, there can be no reproduction; and everything belonging to the earth, whether in its primitive state, or modified by human hands, is submitted to certain and immutable laws of destruction, as permanent and universal as those which produce the planetary motions. The property which, as far as our experience extends, universally belongs to matter, gravitation, is the first and most general cause of change in our terrestrial system; and, whilst it preserves the great ma.s.s of the globe in a uniform state, its influence is continually producing alterations upon the surface. The water, raised in vapour by the solar heat, is precipitated by the cool air in the atmosphere; it is carried down by gravitation to the surface, and gains its mechanical force from this law.

Whatever is elevated above the superfices by the powers of vegetation or animal life, or by the efforts of man, by gravitation constantly tends to the common centre of attraction; and the great reason of the duration of the pyramid above all other forms is, that it is most fitted to resist the force of gravitation. The arch, the pillar, and all perpendicular constructions, are liable to fall when a degradation from chemical or mechanical causes takes place in their inferior parts. The forms upon the surface of the globe are preserved from the influence of gravitation by the attraction of cohesion, or by chemical attraction; but if their parts had freedom of motion, they would all be levelled by this power, gravitation, and the globe would appear as a plane and smooth oblate spheroid, flattened at the poles. The attraction of cohesion or chemical attraction, in its most energetic state, is not liable to be destroyed by gravitation; this power only a.s.sists the agencies of other causes of degradation. Attraction, of whatever kind, tends, as it were, to produce rest--a sort of eternal sleep in Nature. The great antagonist power is heat. By the influence of the sun the globe is exposed to great varieties of temperature; an addition of heat expands bodies, and an abstraction of heat causes them to contract; by variation of heat, certain kinds of matter are rendered fluid, or elastic, and changes from fluids into solids, or from solids or fluids into elastic substances, and _vice versa_, are produced; and all these phenomena are connected with alterations tending to the decay or destruction of bodies. It is not probable that the mere contraction or expansion of a solid, from the subtraction or addition of heat, tends to loosen its parts; but if water exists in these parts, then its expansion, either in becoming vapour or ice, tends not only to diminish their cohesion, but to break them into fragments. There is, you know, a very remarkable property of water--its expansion by cooling, and at the time of becoming ice--and this is a great cause of destruction in the northern climates; for where ice forms in the crevices or cavities of stones, or when water which has penetrated into cement freezes, its expansion acts with the force of the lever or the screw in destroying or separating the parts of bodies. The mechanical powers of water, as rain, hail, or snow, in descending from the atmosphere, are not entirely without effect; for in acting upon the projections of solids, drops of water or particles of snow, and still more of hail, have a power of abrasion, and a very soft substance, from its ma.s.s a.s.sisting gravitation, may break a much harder one. The glacier, by its motion, grinds into powder the surface of the granite rock; and the Alpine torrents, that have their origin under glaciers, are always turbid, from the destruction of the rocks on which the glacier is formed. The effect of a torrent in deepening its bed will explain the mechanical agency of fluid-water, though this effect is infinitely increased, and sometimes almost entirely dependent, upon the solid matters which are carried down by it. An angular fragment of stone in the course of ages moved in the cavity of a rock makes a deep round excavation, and is worn itself into a spherical form. A torrent of rain flowing down the side of a building carries with it the silicious dust, or sand, or matter which the wind has deposited there, and acts upon a scale infinitely more minute, but according to the same law. The buildings of ancient Rome have not only been liable to the constant operation of the rain-courses, or minute torrents produced by rains, but even the Tiber, swollen with floods of the Sabine mountains and the Apennines, has often entered into the city, and a winter seldom pa.s.ses away in which the area of the Pantheon has not been filled with water, and the reflection of the cupola seen in a smooth lake below. The monuments of Egypt are perhaps the most ancient and permanent of those belonging to the earth, and in that country rain is almost unknown. And all the causes of degradation connected with the agency of water act more in the temperate climates than in the hot ones, and most of all in those countries where the inequalities of temperature are greatest. The mechanical effects of air are princ.i.p.ally in the action of winds in a.s.sisting the operation of gravitation, and in abrading by dust, sand, stones, and atmospheric water. These effects, unless it be in the case of a building blown down by a tempest, are imperceptible in days, or even years; yet a gentle current of air carrying the silicious sand of the desert, or the dust of a road for ages against the face of a structure, must ultimately tend to injure it, for with infinite or unlimited duration, an extremely small cause will produce a very great effect. The mechanical agency of electricity is very limited; the effects of lightning have, however, been witnessed, even in some of the great monuments of antiquity, the Colosaeum at Rome, for instance; and only last year, in a violent thunderstorm, some of the marble, I have been informed, was struck from the top of one of the arches in this building, and a perpendicular rent made, of some feet in diameter. But the chemical effects of electricity, though excessively slow and gradual, yet are much more efficient in the great work of destruction. It is to the general chemical doctrines of the changes produced by this powerful agent that I must now direct your especial attention.

_Eub_.--Would not the consideration of the subject have been more distinct, and your explanations of the phenomena more simple, had you commenced by dividing the causes of change into mechanical and chemical; if you had first considered them separately, and then their joint effects?

_The Unknown_.--The order I have adopted is not very remote from this.

But I was perhaps wrong in treating first of the agency of gravitation, which owes almost all its powers to the operation of other causes. In consequence of your hint, I shall alter my plan a little, and consider first the chemical agency of water, then that of air, and lastly that of electricity. In every species of chemical change, temperature is concerned. But unless the results of volcanoes and earthquakes be directly referred to this power, it has no chemical effect in relation to the changes ascribed to time simply considered as heat, but its operations, which are the most important belonging to the terrestrial cycle of changes, are blended with, or bring into activity, those of other agents. One of the most distinct and destructive agencies of water depends upon its solvent powers, which are usually greatest when its temperature is highest. Water is capable of dissolving, in larger or smaller proportions, most compound bodies, and the calcareous and alkaline elements of stones are particularly liable to this kind of operation. When water holds in solution carbonic acid, which is always the case when it is precipitated from the atmosphere, its power of dissolving carbonate of lime is very much increased, and in the neighbourhood of great cities, where the atmosphere contains a large proportion of this principle, the solvent powers of rain upon the marble exposed to it must be greatest. Whoever examines the marble statues in the British Museum, which have been removed from the exterior of the Parthenon, will be convinced that they have suffered from this agency; and an effect distinct in the pure atmosphere and temperate climate of Athens, must be upon a higher scale in the vicinity of other great European cities, where the consumption of fuel produces carbonic acid in large quant.i.ties. Metallic substances, such as iron, copper, bronze, bra.s.s, tin, and lead, whether they exist in stones, or are used for support or connection in buildings, are liable to be corroded by water holding in solution the principles of the atmosphere; and the rust and corrosion, which are made, poetically, qualities of time, depend upon the oxidating powers of water, which by supplying oxygen in a dissolved or condensed state enables the metals to form new combinations. All the vegetable substances, exposed to water and air, are liable to decay, and even the vapour in the air, attracted by wood, gradually reacts upon its fibres and a.s.sists decomposition, or enables its elements to take new arrangements. Hence it is that none of the roofs of ancient buildings more than a thousand years old remain, unless it be such as are constructed of stone, as those of the Pantheon of Rome and the tomb of Theodoric at Ravenna, the cupola of which is composed of a single block of marble. The pictures of the Greek masters, which were painted on the wood of the abies, or pine of the Mediterranean, likewise, as we are informed by Pliny, owed their destruction not to a change in the colours, not to the alteration of the calcareous ground on which they were painted, but to the decay of the tablets of wood on which the intonaco or stucco was laid. Amongst the substances employed in building, wood, iron, tin, and lead, are most liable to decay from the operation of water, then marble, when exposed to its influence in the fluid form; bra.s.s, copper, granite, sienite, and porphyry are more durable. But in stones, much depends upon the peculiar nature of their const.i.tuent parts; when the feldspar of the granite rocks contains little alkali or calcareous earth, it is a very permanent stone; but, when in granite, porphyry, or sienite, either the feldspar contains much alkaline matter, or the mica, schorl, or hornblende much protoxide of iron, the action of water containing oxygen and carbonic acid on the ferruginous elements tends to produce the disintegration of the stone. The red granite, black sienite, and red porphyry of Egypt, which are seen at Rome in obelisks, columns, and sarcophagi, are amongst the most durable compound stones; but the grey granites of Corsica and Elba are extremely liable to undergo alteration: the feldspar contains much alkaline matter; and the mica and schorl, much protoxide of iron. A remarkable instance of the decay of granite may be seen in the Hanging Tower of Pisa; whilst the marble pillars in the bas.e.m.e.nt remain scarcely altered, the granite ones have lost a considerable portion of their surface, which falls off continually in scales, and exhibits everywhere stains from the formation of peroxide of iron. The kaolin, or clay, used in most countries for the manufacture of fine porcelain or china, is generally produced from the feldspar of decomposing granite, in which the cause of decay is the dissolution and separation of the alkaline ingredients.

_Eub_.--I have seen serpentines, basalts, and lavas which internally were dark, and which from their weight, I should suppose, must contain oxide of iron, superficially brown or red, and decomposing. Undoubtedly this was from the action of water impregnated with air upon their ferruginous elements.

_The Unknown_.--You are perfectly right. There are few compound stones, possessing a considerable specific gravity, which are not liable to change from this cause; and oxide of iron amongst the metallic substances anciently known, is the most generally diffused in nature, and most concerned in the changes which take place on the surface of the globe.

The chemical action of carbonic acid is so much connected with that of water, that it is scarcely possible to speak of them separately, as must be evident from what I have before said; but the same action which is exerted by the acid dissolved in water is likewise exerted by it in its elastic state, and in this case the facility with which the quant.i.ty is changed makes up for the difference of the degree of condensation. There is no reason to believe that the azote of the atmosphere has any considerable action in producing changes of the nature we are studying on the surface; the aqueous vapour, the oxygen and the carbonic acid gas, are, however, constantly in combined activity, and above all the oxygen.

And, whilst water, uniting its effects with those of carbonic acid, tends to disintegrate the parts of stones, the oxygen acts upon vegetable matter. And this great chemical agent is at once necessary, in all the processes of life and in all those of decay, in which Nature, as it were, takes again to herself those instruments, organs, and powers, which had for a while been borrowed and employed for the purpose or the wants of the living principle. Almost everything effected by rapid combinations in combustion may also be effected gradually by the slow absorption of oxygen; and though the productions of the animal and vegetable kingdom are much more submitted to the power of atmospheric agents than those of the mineral kingdom, yet, as in the instances which have just been mentioned, oxygen gradually destroys the equilibrium of the elements of stones, and tends to reduce into powder, to render fit for soils, even the hardest aggregates belonging to our globe. Electricity, as a chemical agent, may be considered not only as directly producing an infinite variety of changes, but likewise as influencing almost all which take place. There are not two substances on the surface of the globe that are not in different electrical relations to each other; and chemical attraction itself seems to be a peculiar form of the exhibition of electrical attraction; and wherever the atmosphere, or water, or any part of the surface of the earth gains acc.u.mulated electricity of a different kind from the contiguous surfaces, the tendency of this electricity is to produce new arrangements of the parts of these surfaces; thus a positively electrified cloud, acting even at a great distance on a moistened stone, tends to attract its oxygenous, or acidiform or acid, ingredients, and a negatively electrified cloud has the same effect upon its earthy, alkaline, or metallic matter. And the silent and slow operation of electricity is much more important in the economy of Nature than its grand and impressive operation in lightning and thunder. The chemical agencies of water and air are a.s.sisted by those of electricity; and their joint effects combined with those of gravitation and the mechanical ones I first described are sufficient to account for the results of time. But the physical powers of Nature in producing decay are a.s.sisted likewise by certain agencies or energies of organised beings. A polished surface of a building or a statue is no sooner made rough from the causes that have been mentioned than the seeds of lichens and mosses, which are constantly floating in our atmosphere, make it a place of repose, grow, and increase, and from their death, their decay, and decomposition carbonaceous matter is produced, and at length a soil is formed, in which gra.s.s can fix its roots. In the crevices of walls, where this soil is washed down, even the seeds of trees grow, and, gradually as a building becomes more ruined, ivy and other parasitical plants cover it. Even the animal creation lends its aid in the process of destruction when man no longer labours for the conservation of his works. The fox burrows amongst ruins, bats and birds nestle in the cavities in walls, the snake and the lizard likewise make them their habitation. Insects act upon a smaller scale, but by their united energies sometimes produce great effect; the ant, by establishing her colony and forming her magazines, often saps the foundations of the strongest buildings, and the most insignificant creatures triumph, as it were, over the grandest works of man. Add to these sure and slow operations the devastations of war, the effects of the destructive zeal of bigotry, the predatory fury of barbarians seeking for concealed wealth under the foundations of buildings, and tearing from them every metallic substance, and it is rather to be wondered that any of the works of the great nations of antiquity are still in existence.

_Phil_.--Your view of the causes of devastation really is a melancholy one. Nor do I see any remedy; the most important causes will always operate. Yet, supposing the constant existence of a highly civilised people, the ravages of time might be repaired, and by defending the finest works of art from the external atmosphere, their changes would be scarcely perceptible.

_Eub_.--I doubt much whether it is for the interests of a people that its public works should be of a durable kind. One of the great causes of the decline of the Roman Empire was that the people of the Republic and of the first empire left nothing for their posterity to do; aqueducts, temples, forums, everything was supplied, and there were no objects to awaken activity, no necessity to stimulate their inventive faculties, and hardly any wants to call forth their industry.

_The Unknown_.--At least, you must allow the importance of preserving objects of the fine arts. Almost everything we have worthy of admiration is owing to what has been preserved from the Greek school, and the nations who have not possessed these works or models have made little or no progress towards perfection. Nor does it seem that a mere imitation of Nature is sufficient to produce the beautiful or perfect; but the climate, the manners, customs, and dress of the people, its genius and taste, all co-operate. Such principles of conservation as Philalethes has referred to are obvious. No works of excellence ought to be exposed to the atmosphere, and it is a great object to preserve them in apartments of equable temperature and extremely dry. The roofs of magnificent buildings should be of materials not likely to be dissolved by water or changed by air. Many electrical conductors should be placed so as to prevent the slow or the rapid effects of atmospheric electricity. In painting, lapis lazuli or coloured hard gla.s.ses, in which the oxides are not liable to change, should be used, and should be laid on marble or stucco encased in stone, and no animal or vegetable substances, except pure carbonaceous matter, should be used in the pigments, and none should be mixed with the varnishes.

_Eub_.--Yet, when all is done that can be done in the work of conservation, it is only producing a difference in the degree of duration. And from the statements that our friend has made it is evident that none of the works of a mortal being can be eternal, as none of the combinations of a limited intellect can be infinite. The operations of Nature, when slow, are no less sure; however man may for a time usurp dominion over her, she is certain of recovering her empire. He converts her rocks, her stones, her trees, into forms of palaces, houses, and ships; he employs the metals found in the bosom of the earth as instruments of power, and the sands and clays which const.i.tute its surface as ornaments and resources of luxury; he imprisons air by water, and tortures water by fire to change or modify or destroy the natural forms of things. But, in some l.u.s.trums his works begin to change, and in a few centuries they decay and are in ruins; and his mighty temples, framed as it were for immortal and divine purposes, and his bridges formed of granite and ribbed with iron, and his walls for defence, and the splendid monuments by which he has endeavoured to give eternity even to his perishable remains, are gradually destroyed; and these structures, which have resisted the waves of the ocean, the tempests of the sky, and the stroke of the lightning, shall yield to the operation of the dews of heaven, of frost, rain, vapour, and imperceptible atmospheric influences; and, as the worm devours the lineaments of his mortal beauty, so the lichens and the moss and the most insignificant plants shall feed upon his columns and his pyramids, and the most humble and insignificant insects shall undermine and sap the foundations of his colossal works, and make their habitations amongst the ruins of his palaces and the falling seats of his earthly glory.

_Phil_.--Your history of the laws of the inevitable destruction of material forms recalls to my memory our discussion at Adelsberg. The changes of the material universe are in harmony with those which belong to the human body, and which you suppose to be the frame or machinery of the sentient principle. May we not venture to imagine that the visible and tangible world, with which we are acquainted by our sensations, bears the same relation to the Divine and Infinite Intelligence that our organs bear to our mind, with this only difference, that in the changes of the divine system there is no decay, there being in the order of things a perfect unity, and all the powers springing from one will and being a consequence of that will, are perfectly and unalterably balanced. Newton seemed to apprehend, that in the laws of the planetary motions there was a principle which would ultimately be the cause of the destruction of the system. Laplace, by pursuing and refining the principles of our great philosopher, has proved that what appeared sources of disorder are, in fact, the perfecting machinery of the system, and that the principle of conservation is as eternal as that of motion.

_The Unknown_.--I dare not offer any speculations on this grand and awful subject. We can hardly comprehend the cause of a simple atmospheric phenomenon, such as the fall of a heavy body from a meteor; we cannot even embrace in one view the millionth part of the objects surrounding us, and yet we have the presumption to reason upon the infinite universe and the eternal mind by which it was created and is governed. On these subjects I have no confidence in reason, I trust only to faith; and, as far as we ought to inquire, we have no other guide but revelation.

_Phil_.--I agree with you that whenever we attempt metaphysical speculations, we must begin with a foundation of faith. And being sure from revelation that G.o.d is omnipotent and omnipresent, it appears to me no improper use of our faculties to trace even in the natural universe the acts of His power and the results of His wisdom, and to draw parallels from the infinite to the finite mind. Remember, we are taught that man was created in the image of G.o.d, and, I think, it cannot be doubted that in the progress of society man has been made a great instrument by his energies and labours for improving the moral universe.

Compare the Greeks and Romans with the a.s.syrians and Babylonians, and the ancient Greeks and Romans with the nations of modern Christendom, and it cannot, I think, be questioned that there has been a great superiority in the latter nations, and that their improvements have been subservient to a more exalted state of intellectual and religious existence. If this little globe has been so modified by its powerful and active inhabitants, I cannot help thinking that in other systems beings of a superior nature, under the influence of a divine will, may act n.o.bler parts. We know from the sacred writings that there are intelligences of a higher nature than man, and I cannot help sometimes referring to my vision in the Colosaeum, and in supposing some acts of power of those genii or seraphs similar to those which I have imagined in the higher planetary systems. There is much reason to infer from astronomical observations that great changes take place in the system of the fixed stars: Sir William Herschel, indeed, seems to have believed that he saw nebulous or luminous matter in the process of forming suns, and there are some astronomers who believe that stars have been extinct; but it is more probable that they have disappeared from peculiar motions. It is, perhaps, rather a poetical than a philosophical idea, yet I cannot help forming the opinion that genii or seraphic intelligences may inhabit these systems and may be the ministers of the eternal mind in producing changes in them similar to those which have taken place on the earth. Time is almost a human word and change entirely a human idea; in the system of Nature we should rather say progress than change. The sun appears to sink in the ocean in darkness, but it rises in another hemisphere; the ruins of a city fall, but they are often used to form more magnificent structures as at Rome; but, even when they are destroyed, so as to produce only dust, Nature a.s.serts her empire over them, and the vegetable world rises in constant youth, and--in a period of annual successions, by the labours of man providing food--vitality, and beauty upon the wrecks of monuments, which were once raised for purposes of glory, but which are now applied to objects of utility.