Anaxagoras, residing at Athens and intimately connected with Perikles, incurred not only unpopularity, but even legal prosecution, by the tenor of his philosophical opinions, especially those on astronomy. To Greeks who believed in Helios and Selênê as not merely living beings but Deities, his declaration that the Sun was a luminous and fiery stone, and the Moon an earthy mass, appeared alike absurd and impious. Such was the judgment of Sokrates, Plato, and Xenophon, as well as of Aristophanes and the general Athenian public.[180] Anaxagoras was threatened with indictment for blasphemy, so that Perikles was compelled to send him away from Athens. [Footnote 180: Plato, Apol. So. c. 14; Xenoph. Memor. iv. 7.] That physical enquiries into the nature of things, and attempts to substitute scientific theories in place of the personal agency of the Gods, were repugnant to the religious feelings of the Greeks, has been already remarked.[181] Yet most of the other contemporary philosophers must have been open to this reproach, not less than Anaxagoras; and we learn that the Apolloniate Diogenes left Athens from the same cause. If others escaped the like prosecution which fell upon Anaxagoras, we may probably ascribe this fact to the state of political party at Athens, and to the intimacy of the latter with Perikles. The numerous political enemies of that great man might fairly hope to discredit him in the public mind--at the very least to vex and embarrass him--by procuring the trial and condemnation of Anaxagoras. Against other philosophers, even when propounding doctrines not less obnoxious respecting the celestial bodies, there was not the same collateral motive to stimulate the aggressive hostility of individuals. [Footnote 181: Plutarch, Nikias, 23.] [Side-note: Diogenes of Apollonia recognises one primordial element.] Contemporary with Anaxagoras--yet somewhat younger, as far as we can judge, upon doubtful evidence--lived the philosopher Diogenes, a native of Apollonia in Krete. Of his life we know nothing except that he taught during some time at Athens, which city he was forced to quit on the same ground as Anaxagoras. Accusations of impiety were either brought or threatened against him:[182] physical philosophy being offensive generally to the received religious sentiment, which was specially awakened and appealed to by the political opponents of Perikles.