t with the eternal Being,--the supreme harmony which
rules over all." To trace the divine energy of life in all things was
the general problem of the philosophy of Heraclitus, and this spirit was
akin to the pantheism of the East. But he was one of the greatest
speculative intellects that preceded Plato, and of all the physical
theorists arrived nearest to spiritual truth. He taught the germs of
what was afterward more completely developed. "From his theory of
perpetual fluxion," says Archer Butler, "Plato derived the necessity of
seeking a stable basis for the universal system in his world of ideas."
Heraclitus was, however, an obscure writer, and moreover cynical
and arrogant.

Anaxagoras, the most famous of the Ionian philosophers, was born 500
B.C., and belonged to a rich and noble family. Regarding philosophy as
the noblest pursuit of earth, he abandoned his inheritance for the study
of Nature. He went to Athens in the most brilliant period of her history,
and had Pericles, Euripides, and Socrates for pupils. He taught that the
great moving force of Nature was intellect ([Greek: nous]). Intelligence
was the cause of the world and of order, and mind was the principle of
motion; yet this intelligence was not a moral intelligence, but simply
the _primum mobile_,--the all-knowing motive force by which the order of
Nature is effected. He thus laid the foundation of a new system, under
which the Attic philosophers sought to explain Nature, by regarding as
the cause of all things, not _matter_ in its different elements, but
rather _mind_, thought, intelligence, which both knows and acts,--a
grand conception, unrivalled in ancient speculation. This explanation of
material phenomena by intellectual causes was the peculiar merit of
Anaxagoras, and places him in a very high rank among the thinkers of the
world. Moreover, he recognized the reason as the only faculty by which
we become cognizant of truth, the senses being too weak to discover the
real component particles of things. Like all the great inquirers, he was
impressed with the limited degree of positive knowledge compared with
what there is to be learned. "Nothing," says he, "can be known; nothing
is certain; sense is limited, intellect is weak, life is short,"--the
complaint, not of a sceptic, but of a man overwhelmed with the sense of
his incapacity to solve the problems which arose before his active mind.
Anaxagoras thought that this spirit ([Greek: nous]) gave to a