Heroes of science

by P. Martin Duncan

CHAPTER IX.
HEROES OF GEOLOGY.

The rise of the science which treats of the ancient history of the earth—Students of the present changes, which are the examples by which the past may be comprehended—The Greeks—The life of Pythagoras; a notice of the geology of Aristoteles—Strabo’s life—The nature of fossils and the life of Steno.

As was the case in the other branches of natural history already noticed, the Greeks knew much more about geology than did the nations of the rest of Europe, subsequently, for nearly seventeen hundred years. The first recorded teacher of the ancient history of the earth was Pythagoras, who was born on the island of Samos, about the year 570 B.C. By his mother’s side he was connected with the principal families of the island, and his father appears to have been a Phœnician or a Tyrrhenian of Lemnos. There is nothing known about his childhood, and it is evident that he studied under the great philosophers of his age in Greece. But he wanted further information, and therefore travelled into Egypt, and thence into Chaldæa. Polycrates, the ruler of the island in which Pythagoras was born, appears to have assisted him with the Egyptians by introductions. The traveller noticed not only the habits and customs of the people he visited, but also the aspect of the countries, and the method by which nature wore the earth, and produced changes on the surface of the ground. He appears to have been much struck with the periodical nature of many natural events, such as the succession of the seasons, the time of rain and inundation, and of great heat, and of all the common examples with which everyone is familiar at the present day. Returning home he soon became aware that he could not teach, unreservedly, what he had learned and discovered during his travels, for fear of Polycrates, and he left the island. Finally he settled at Croton, in southern Italy, and he appears to have chosen the locality, in order to propagate his moral and political, as well as scientific opinions. Unfortunately, this ardent scholar and teacher did not write any books, but left that task to his pupils and successors, so that much good sense is mixed with much nonsense in the so-called doctrines of Pythagoras which came from them. Some of his opinions are very remarkable and striking, and he introduced into his own country the statements of the Eastern nations, that there has been a gradual deterioration of the human race from an original state of virtue and happiness. But his principal work regarding the earth has descended to us through the poet Ovid, and it is most interesting. Pythagoras insisted that there was a perpetual and gradual system of change, inherent in the earth. This idea, which came into his mind from the results of observation, he did not apply to very remote ages, or to what is now called the ancient history of the globe. He simply insisted on modern changes. Really this limiting of his thought was in the true scientific spirit, and he dealt with what was true and proveable so far as he was concerned. It might be supposed that the present changes cannot come within the studies of the geologist, but they really do so, because, as will be noticed further on in considering the life of Hutton, the past history of the earth can only be comprehended by studying the present state of things. Pythagoras cleared the way, and made a path for the geologist. He is said by Ovid to have taught as follows:—

“Nothing perishes in this world, but things simply vary and change their form. To be born means simply that a thing begins to be something different from what it was before; and dying is ceasing from being the same thing. Solid land has been converted into sea. Sea has been changed into land; marine shells lie far distant from the deep, and the anchor has been found on the summit of the hills. Valleys have been excavated by running water, and floods have washed down hills into the sea. Marshes have become dry ground. Dry lands have changed into stagnant pools. During earthquakes some springs have been closed up, and new ones have broken out. Rivers have deserted their channels, and have been reborn elsewhere; as the Erasinus, in Greece, and Mysius, in Asia. The waters of some rivers, formerly sweet, have become bitter, as those of Anigrus, in Greece. Islands have become connected with the main land, by the growth of deltas and new deposits. Peninsulas have been divided from the main land, and have become islands, as Leucadia; and according to tradition, Sicily, the sea having carried away the isthmus. Land has been submerged by earthquakes. The Grecian cities of Helice and Burris, for example, are to be seen under the sea, with their walls inclined. Plains have been upheaved into hills by the confined air seeking vent, as at Trœzene, in the Peloponnesus. There are streams which have a petrifying power, and convert the substances which they touch into marble. Volcano vents shift their positions. There was a time when Etna was not a burning mountain, and the time will come when it will cease to burn; whether it be that some caverns be closed up by the movements of the earth and others opened, or whether the fuel is finally exhausted.”

Of course there are several errors in these statements, and especially those which relate to the causes of volcanic vents are absurd. Pythagoras also noticed the changes in the animal kingdoms, such as the metamorphoses of insects. Besides being a naturalist this great man taught some most extraordinary doctrines for his time of the world and nation. He stated that virtue was with him and his followers, a harmony, unity, and an endeavour to resemble the Deity. The whole life of man should be an attempt to represent, on earth, the beauty and harmony displayed in the order of the universe. The mind should have the body and the passions under perfect control; the gods should be worshipped by simple purifications and offerings, and above all by sincerity and purity of heart. Pythagoras, by his good teaching and example, established a great school of philosophy, which influenced the world subsequently in a marked manner. A political riot dispersed his followers, and he died about 504 B.C.

A notice of the life of Aristoteles as botanist and zoologist has already been given, and now a few words must be said about the opinions held by this very remarkable man regarding changes in the earth. He progressed beyond Pythagoras, for he refers to many examples of changes now constantly going on, and insists, emphatically, on the great results which they must produce in the lapse of ages. The changes of the earth, he says, are so slow in comparison to the duration of our lives, that they are overlooked, and the migrations of people after great catastrophes, and their removal to other regions, cause the event to be forgotten. In one work Aristoteles wrote: “The distribution of land and sea, in particular regions, does not endure throughout all time, but it becomes sea in those parts where it was land, and again it becomes land where it was sea; and there is reason for thinking that these changes take place according to a certain system and within a certain period. Everything changes in the course of time.”

There was a great geographer called Strabo, about whose life little is known, except that he travelled far and wide in Europe and North Africa, and wrote largely on the earth. He did not content himself with simple geography, however, for he entered into a discussion, which was a very common one in those days, as it has been since, concerning the nature of the fossil shells which are found in strata or layers of the earth remote from the sea. He attributed the collecting of the shells where they are found to the former subsidence of the land, and not to the rising of the sea. It is not, he said, because the lands covered by seas were originally at different altitudes, that the waters have risen or subsided or receded from some parts and inundated others, but the reason is, that the same land is sometimes raised up and sometimes depressed, so that it either overflows or returns to its own place again. We must therefore ascribe the cause to the ground, either to that ground which is under the sea or to that which becomes flooded by it, but rather to that which lies beneath the sea, for this is more moveable, and on account of its humidity can be altered with greater celerity. This philosopher clearly laid down the law that the general level of the sea has remained the same, but that it has been and is the land which has been or is upheaved or subsided. It is a fundamental truth on which much of the science of geology depends. He moreover asserted that volcanoes were safety-valves, and were the result of subterranean convulsions.

These were the principal writers which influenced geology in the days before the Christian era, and it is to be noticed that they did not treat of the construction of the rocks, of the succession of the layers or strata, or of much concerning the ancient history of the globe. But they taught, wisely and admirably, the nature of modern changes, and believed that these and the older ones they could comprehend, were part of a scheme, and were produced by natural causes, in the course of events.