DIogenes of Apollonia, in the island of Crete, held
a considerable rank among the philosophers who taught in
Ionia before Socrates appeared at Athens. He was the
scholar and successor of Anaximenes, and in some mea-
sure rectified his master's opinion concerning air being
the cause of all things. It is said that he was the first
who observed that air was capable of condensation and
rarefaction. He passed for an excellent philosopher, and
died about the 450th year before the Christian era.