ABSTRACT
An entire era in the history of biology closes with the philosophers that have here just been characterized — Democritus, Hippocrates, and his school — an era which may properly be called the era of natural-philosophical speculation. The results achieved by their researches cannot be regarded as anything but magnificent; for the first time in the history of humanity to have built up a real natural science is an achievement worthy of the highest admiration, however modest the results may have been in certain details. This research work had so far been directed by three illustrious representatives, Anaximander, Empedocles, and Democritus. All of them sought an explanation of existence as a natural course of events; in this direction Democritus proceeded as far as human thought has at any period proved capable of going. Nevertheless, even in his own lifetime the revolution was being prepared which was shortly to lead Greek thought in entirely different directions. The first ideas on which this change was based originated, as hinted above, from the school of the Sophists. The new principle that they taught was subjectivity: "Man is the measure of all things." To this really true assertion the ancient "physicists" could make no objection; indeed, their cosmic explanations were as numerous as themselves, and each one of them could only declare dogmatically that his own views were the true ones and thereupon produce a number of more or less illogical arguments in support of them. The claim of the Sophists as to man's being the measure of all things thus for the time did away with all objective explanations of natural phenomena, for what was the use of disputing about matters which all viewed from different standpoints if all could be equally right? Sophistry itself, however, when consistently applied, led to pure nihilism, both intellectual, in that the object was, by means of ingenious turns of phrase ("sophisms"), to prove absolutely anything, and moral, in that all generally accepted sound traditions were held in contempt as laying a restraint upon the individual's freedom of action. If all scientific thought were not to be destroyed altogether, its preservation must be sought by turning the whole trend of thinking into quite a different direction. And this was found by maintaining that human thought, however much it may 31be the measure of all things, such as they appear here on earth, is nevertheless itself subject to eternal laws, more infallible than those which the old physicists saw in existence. The men who thus saved the Greek philosophy from degenerating into empty rhetoric and worthless quibbles were two Athenians, Socrates and his disciple Plato. Socrates worked exclusively in the ethical sphere; in this he sought for standards binding for all and emanating, not from ancient tradition, but from the conscience of the private individual. "Anyone can become virtuous if only he accepts a knowledge of virtue"; that is his principal doctrine, and this knowledge he for his own part derived from a divine voice in himself, which he desired also to awaken in his fellow human beings. Nature did not interest him in the least; the streets of Athens were his haunt, he said, and neither trees nor stones had anything to teach him.
