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 mass 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