Arcesilaus, a Greek philosopher, the founder of the Middle Academy, born at Pitane in Aeolis about 316 B. C, died about 241. He was originally intended for a rhetorician, but v-iiile pursuing his studies at Athens decided to devote himself entirely to philosophy, and succeeded Crates in the chair of the academy of Athens. From the little we know of his opinions, it seems that he was a skeptic, but not in the Pyrrhonic sense of that term; and his celebrated saying, " that he knew nothing, not even his own ignorance," seems to have been but an utterance of humility. He was also distinguished from the pure Pyrrhonists by his predilection for questions appertaining to practical life, and by the undeviating moderation of his tone.