unable to satisfy myself as to its cause. The views of the stranger appeared to me now to make it probable that the calcareous water had issued from ancient leaks in the aqueduct and formed a hillock that had encased the bricks of the erection, which in other parts, where not encrusted by travertine, had become entirely decayed, degraded, and removed from the soil. I mentioned the circumstance and my suspicion of its nature. The stranger said: "You are perfectly correct in your idea. I know the spot well, and if you had not mentioned it I should probably have quoted it as an instance in which the works of art are preserved, as it were, by the accidents of Nature. I was so struck by this appearance last year that I had the travertine partially removed by some workmen, and I found beneath it the canal of the aqueduct in a perfect state, and the bricks of the arches as uninjured as if freshly laid." The stranger had hardly concluded this sentence when he was interrupted by Onuphrio, who said, "I have always supposed that in every geological system water is considered as the cause of the destruction or degradation of the surface, but in all the instances that you have mentioned it appears rather as a conservative power, not destroying but rather producing." "It is the general vice of philosophical systems," replied the stranger, "that they are usually founded upon a few facts, which they well explain, and are extended by the human fancy to all the phenomena of Nature, to many of which they must be contradictory. The human intellectual powers are so feeble that they can with difficulty embrace a single series of phenomena, and they consequently must fail when extended to the whole of Nature. Water by its common operation, as poured down from the atmosphere in rain and torrents, tends to level and degrade the surface, and carries the material of the land into the bosom of the ocean. Fire, on the contrary, in volcanic eruptions usually raises mountains, exalts the surface, and creates islands even in the midst of the sea. But these laws are not invariable, as the instances to which we have just referred prove, and parts of the surface of the globe are sometimes destroyed even by fire, of which examples may be seen in the Phlegraean fields, and islands raised by one volcanic eruption have been immerged in the sea by another. There are, in fact, no accidents in Nature; what we call accidents are the results of general laws in particular operation, but we cannot deduce these laws from the particular operation or the general order from the partial result." Ambrosio said to the stranger: "You appear, sir, to have paid so much attention to physical phenomena that few things would give us more pleasure than to know your opinion respecting the early changes and physical history of the globe, for I perceive you do not belong to the modern geological schools." The stranger said, "I have certainly formed opinions or rather speculations