Sphaerus


Sphaerus of Borysthenes or the Bosphorus, was a Stoic philosopher.

Life

Sphaerus studied first under Zeno of Citium, and afterwards under Cleanthes. He taught in Sparta, where he acted as advisor to Cleomenes III. He moved to Alexandria at some point, where he lived in the court of Ptolemy IV Philopator.

Ideas

Little survives of his works, but Sphaerus had a considerable reputation among the Stoics for the accuracy of his definitions.
Diogenes Laërtius and Athenaeus tell a story of how he once saved himself from admitting that he had been deceived by a trick played upon him by King Ptolemy:
And once, when there was a discussion concerning the question whether a wise man would allow himself to be guided by opinion, and when Sphaerus affirmed that he would not, the king, wishing to refute him, ordered some pomegranates of wax to be set before him; and when Sphaerus was deceived by them, the king shouted that he had given his assent to a false perception. But Sphaerus answered very neatly, that he had not given his assent to the fact that they were pomegranates, but to the fact that it was probable that they might be pomegranates. And that a perception which could be comprehended differed from one that was only probable.

Writings

According to Diogenes Laërtius, Sphaerus wrote the following works: