But here, as many other scientists after him were to discover, he trod upon dangerous ground, for he discussed something with which people were familiar. The sun and the moon were distant orbs. The average Greek did not care what names the philosopher wished to call them. But when the professor began to argue that all things had gradually grown and developed out of a vague substance called “original matter”—then he went decidedly too far. Such an assertion was in flat contradiction with the story of Deucalion and Pyrrha, who after the great flood had re-populated the world by turning bits of stone into men and women. To deny the truth of a most solemn tale which all little Greek boys and girls had been taught in their early childhood was most dangerous to the safety of established society. It would make the children doubt the wisdom of their elders and that would never do. Hence Anaxagoras was made the subject of a formidable attack on the part of the Athenian Parents’ League.

During the monarchy and the early days of the republic, the rulers of the city would have been more than able to protect a teacher of unpopular doctrines from the foolish hostility of the illiterate Attic peasants. But Athens by this time had become a full-fledged democracy and the freedom of the individual was no longer what it used to be. Furthermore, Pericles, just then in disgrace with the majority of the people, was himself a favorite pupil of the great astronomer, and the legal prosecution of Anaxagoras was welcomed as an excellent political move against the city’s old dictator.

A priest by the name of Diopheites, who also was a ward-leader in one of the most densely populated suburbs, got a law passed which demanded “the immediate prosecution of all those who disbelieved in the established religion or held theories of their own about certain divine things.” Under this law, Anaxagoras was actually thrown into prison. Finally, however, the better elements in the city prevailed. Anaxagoras was allowed to go free after the payment of a small fine and move to Lampsacus in Asia Minor where he died, full of years and honor, in the year 428 B.C.

His case shows how little is ever accomplished by the official suppression of scientific theories. For although Anaxagoras was forced to leave Athens, his ideas remained behind and two centuries later they came to the notice of one Aristotle, who in turn used them as a basis for many of his own scientific speculations. Reaching merrily across a thousand years of darkness, he handed them on to one Abul-Walid Muhammad ibn-Ahmad (commonly known as Averroës), the great Arab physician who in turn popularized them among the students of the Moorish universities of southern Spain. Then, together with his own observations, he wrote them down in a number of books. These were duly carried across the Pyrenees until they reached the universities of Paris and Boulogne. There they were translated into Latin and French and English and so thoroughly were they accepted by the people of western and northern Europe that today they have become an integral part of every primer of science and are considered as harmless as the tables of multiplication.

But to return to Anaxagoras. For almost an entire generation after his trial, Greek scientists were allowed to teach doctrines which were at variance with popular belief. And then, during the last years of the fifth century, a second case took place.

The victim this time was a certain Protagoras, a wandering teacher who hailed from the village of Abdera, an Ionian colony in northern Greece. This spot already enjoyed a doubtful reputation as the birthplace of Democritus, the original “laughing philosopher,” who had laid down the law that “only that society is worth while which offers to the largest number of people the greatest amount of happiness obtainable with the smallest amount of pain,” and who therefore was regarded as a good deal of a radical and a fellow who should be under constant police supervision.

Protagoras, deeply impressed by this doctrine, went to Athens and there, after many years of study, proclaimed that man was the measure of all things, that life was too short to waste valuable time upon an inquiry into the doubtful existence of any Gods, and that all energies ought to be used for the purpose of making existence more beautiful and more thoroughly enjoyable.

This statement, of course, went to the very root of the matter and it was bound to shock the faithful more than anything that had ever been written or said. Furthermore it was made during a very serious crisis in the war between Athens and Sparta and the people, after a long series of defeats and pestilence, were in a state of utter despair. Most evidently it was not the right moment to incur the wrath of the Gods by an inquiry into the scope of their supernatural powers. Protagoras was accused of atheism, of “godlessness,” and was told to submit his doctrines to the courts.

Pericles, who could have protected him, was dead and Protagoras, although a scientist, felt little taste for martyrdom.