which Plato was the founder, limited its labours to the
illustration and defence of his doctrines. The Middle Academy,
originating with Arcesilaus, born B.C. 316, maintained a warfare with
the Stoics, developed the doctrine of the uncertainty of sensual
impressions and the nothingness of human knowledge. The New Academy was
founded by Carneades, born B.C. 213, and participated with the preceding
in many of its fundamental positions. On the one side Carneades leans to
scepticism, on the other he accepts probability as his guide. This
school so rapidly degenerated that at last it occupied itself with
rhetoric alone. The gradual increase of scepticism and indifference
throughout this period is obvious enough; thus Arcesilaus said that he
knew nothing, not even his own ignorance, and denied both intellectual
and sensuous knowledge. Carneades, obtaining his views from the old
philosophy, found therein arguments suitable for his purpose against
necessity, God, soothsaying; he did not admit that there is any such
thing as justice in the abstract, declaring that it is a purely
conventional thing; indeed, it was his rhetorical display, alternately
in praise of justice and against it, on the occasion of his visit to
Rome, that led Cato to have him expelled from the city. Though Plato had
been the representative of an age of faith, a secondary analysis of all
his works, implying an exposition of their contradictions, ended in
scepticism. If we may undertake to determine the precise aim of a
philosophy whose representatives stood in such an attitude of rhetorical
duplicity, it may be said to be the demonstration that there is no
criterion of truth in this world. Persuaded thus of the impossibility of
philosophy, Carneades was led to recommend his theory of the probable.
"That which has been most perfectly analyzed and examined, and found to
be devoid of improbability, is the most probable idea." The degeneration
of philosophy now became truly complete, the labours of so many great
men being degraded to rhetorical and artistic purposes. It was seen by
all that Plato had destroyed all trust in the indications of the senses,
and substituted for it the Ideal theory. Aristotle had destroyed that,
and there was nothing left to the world but scepticism. A fourth Academy
was founded by Philo of Larissa, a fifth by Antiochus of Ascalon. It was
reserved for this teacher to attach the Porch to the Academy, and to
merge the doctrines of Plato in