dark, and dense particles which form the lower air.
Rotation takes the latter towards the centre, and out of this the
earth is formed. The earth, as with Anaximenes, is a flat disc, borne
upon the air. The heavenly bodies consist of {103} masses of stone
which have been torn from the earth by the force of its rotation, and
being projected outwards become incandescent through the rapidity of
their movement. The moon is made of earth and reflects the light of
the sun. Anaxagoras was thus the first to give the true cause of the
moon's light. He was also the first to discover the true theory of
eclipses, since he taught that the solar eclipse is due to the
intervention of the moon between the sun and the earth, and that lunar
eclipses arise from the shadow of the earth falling upon the moon. He
believed that there are other worlds besides our own with their own
suns and moons. These worlds are inhabited. The sun, according to
Anaxagoras, is many times as large as the Peloponnese. The origin of
life upon the earth is accounted for by germs which existed in the
atmosphere, and which were brought down into the terrestrial slime by
rain water, and there fructified. Anaxagoras's theory of perception is
the opposite of the theories of Empedocles and the Atomists.
Perception takes place by unlike matter meeting unlike.

Anaxagoras owes his importance in the history of philosophy to the
theory of the Nous. This was the first time that a definite
distinction had been made between the corporeal and incorporeal.
Anaxagoras is the last philosopher of the first period of Greek
philosophy. In the second chapter, [Footnote 9] I observed that this
first period is characterized by the fact that in it the Greek mind
looks only outward upon the external world. It attempts to explain the
operations of nature. It had not yet learned to look inward upon
itself. But the transition to the introspective study of mind is found
in the Nous of {104} Anaxagoras. Mind is now brought to the fore as a
problem for philosophy. To find reason, intelligence, mind, in all
things, in the State, in the individual, in external nature, this is
the characteristic of the second period of Greek philosophy. To have
formulated the antithesis between mind and matter is the most
important work of Anaxagoras.

[Footnote 9: Pages 23-4.]

Secondly, it is to the credit of Anaxagoras that he was the first to
introduce the idea of teleology into philosophy. The system of t