; for he directed his
investigations especially to the discovery of causes.

Besides the infinite number of atoms, he likewise supposed the existence
of an infinite number of worlds, each being kept together by a sort of
shell or skin. He derived the four elements from the form, quality, and
proportionate magnitude of the atoms predominating in each; and in
deriving individual things from atoms, he mainly considered the qualities
of warm and cold; the soul he considered as derived from fire atoms; and
he did not consider mind as anything peculiar, or as a power distinct from
the soul or sensuous perception; but he considered knowledge derived from
reason to be a sensuous perception.

In his ethical philosophy, he considered (as we may see from the _de
Finibus_) the acquisition of peace of mind as the end and ultimate object
of all our actions, and as the last and best fruit of philosophical
inquiry. Temperance and moderation in prosperity and adversity were, in
his eyes, the principal means of acquiring this peace of mind. And he
called those men alone pious and beloved by the Gods who hate whatever is
wrong.

_Empedocles_ was a Sicilian, who flourished about the time when
Thrasydaeus, the son of Theron, was expelled from Agrigentum, to the
tyranny of which he had succeeded; in which revolution he took an active
part: it is even said that the sovereignty of his native city was offered
to and declined by him.

He was a man of great genius and extensive learning; it is not known whose
pupil he was, nor are any of his disciples mentioned except Gorgias. He
was well versed in the tenets of the Eleatic and Pythagorean schools; but
he did not adopt the fundamental principles of either; though he agreed
with Pythagoras in his belief in the metempsychosis, in the influence of
numbers, and in one or two other points; and with the Eleatics in
disbelieving that anything could be generated out of nothing. Aristotle
speaks of him as very much resembling in his opinions Democritus and
Anaxagoras. He was the first who established the number of four elements,
which had been previously pointed out one by one, partly as fundamental
substances, and partly as transitive changes of things coming into
existence. He first suggested the idea of two opposite directions of the
moving power, an attractive and a repelling one: and he believed that
originally these two coexisted in a state of repose and inactivity. He
also assumed a periodical