stamp of genuineness, and similar ideas
recur, more or less completely and variously refracted, in the succeeding
philosophers.

To follow these variations in detail is outside the scope of this
investigation; but it may be of interest to see the form they take in one
of the latest and most advanced representatives of Ionian naturalism. In
Democritus's conception of the universe, personal gods would seem excluded
_a priori_. He works with but three premises: the atoms, their movements,
and empty space. From this everything is derived according to strict
causality. Such phenomena also as thunder and lightning, comets and
eclipses, which were generally ascribed to the gods, are according to his
opinion due to natural causes, whereas people in the olden days were
afraid of them because they believed they were due to the gods.
Nevertheless, he seems, in the first place, to have designated Fire, which
he at the same time recognised as a "soul-substance," as divine, the
cosmic fire being the soul of the world; and secondly, he thought that
there was something real underlying the popular conception of the gods. He
was led to this from a consideration of dreams, which he thought were
images of real objects which entered into the sleeper through the pores of
the body. Now, since gods might be seen in dreams, they must be real
beings. He did actually say that the gods had more senses than the
ordinary five. When he who of all the Greek philosophers went furthest in
a purely mechanical conception of nature took up such an attitude to the
religion of his people, one cannot expect the others, who were less
advanced, to discard it.

Nevertheless, there is a certain probability that some of the later Ionian
naturalists went further in their criticism of the gods of popular belief.
One of them actually came into conflict with popular religion; it will be
natural to begin with him.

Shortly before the outbreak of the Peloponnesian War, Anaxagoras of
Clazomenae was accused of impiety and had to leave Athens, where he had
taken up his abode. The object of the accusation was in reality political;
the idea being to hit Pericles through his friend the naturalist. What
Anaxagoras was charged with was that he had assumed that the heavenly
bodies were natural objects; he had taught that the sun was a red-hot
mass, and that the moon was earth and larger than Peloponnese. To base an
accusation of impiety on this, it was necessary first to carr