(s. v.). We hear nothing of his
personal history till the time when he accompanied his uncle Plato on his third journey to
Syracuse, where he displayed considerable ability and prudence, especially in his amicable
relations with Dion (Dion.
17). And indeed he is not comparable either to Plato or to Aristotle, though the latter
appears, among all his Academic antagonists, to have deemed Speusippus worthy of the honour of
being refuted, and is even said to have purchased his books for three talents (Noct. Att. 3.17). The report
about his sudden fits of anger, his avarice, and his propensity to voluptuousness, are
probably derived from a very impure source : Athenaeus (vii. p. 279e., xii. p. 546d.) and
Diogenes Laertius (4.1, 2; camp. Suid. s.v. Tertullian, Apolog. 100.46)
can adduce as authority for them scarcely any thing more than some abuse in certain letters of
the younger Dionysius, who was banished by Dion, not without the co-operation of Speusippus.
Having been selected by Plato as his successor in the office of president of the Academy, he
was at the head of the school for only eight years (l.c. 4.4, ib. Interp.).
From the list of his numerous dialogues and commentaries Diogenes Laertius gives us an
extract, which contains only titles, which do not always admit of any conclusion as to their
contents, and the scanty notices in other writers furnish us with little that can supply the
void or throw any light upon them. Speusippus seems to have continued Plato's polemical
attacks upon the hedonistic theory of Aristippus (justice and of the citizen, and the fundamental
principles of legislation (
His efforts, however, were especially directed to the bringing together of those things
that were similar as regards their philosophic treatment (Diog. Laert. l.100.5,
Diog. Laert., l.100.2 ; Casaubon is hardly correct in
restricting the word in Arist. Anal. Post. vid. Schol. in
Aristot. ed. Brandis, p. 248a.). With Plato, moreover. he distinguished between that
which is the object of thought, and that which is the object of sensuous perception, between
the cognition of the reason and sensuous perception. He endeavored, however, to show how the
latter can be taken up and transformed into knowledge, by the assumption of a perception,
which, by participation in rational truth (rational perception of them (Sext. Emp. ad
v. Math. 7.145, &c.). The idea of essence also he endeavoured
to seize more distinctly by separating its kinds, the difference between which he considered
would result from the difference between the principia on which they are based. Thus he
distinguished essences of numbers, of size, of soul, while Plato had referred them, as
separate definitudes, to the ideal numbers (Arist. Met. 6.2, 11, 12.10,
de Anima, 1.2; Iamblich. apud Stob. Eclog. 1.862).
Nevertheless Speusippus also must have recognised something common in those different kinds
of essences, inasmuch as in the first place he set out from absolute unity, and regarded it
as a formal principium which they had in common (Arist. Met. 6.2, p.
1028, 14.3, 13.9 ; comp. Ravaisson, Speusippi de Primis Rerum Principiis
Placita, Paris, 1838), and in the next place he appears to have presupposed multitude
and multiformity as a common primary element in their composition. But it is only the
difficulties which led him to make this and similar deviations from the Platonic doctrine, of
which we can get any clear idea, not the mode in which he thought he had obviated those
difficulties by distinguishing different kinds of principia. The criticism of Aristotle,
directed apparently against Speusippus, shows how little satisfied he was with the
modification of the original Platonic doctrine. With this deviation from Plato's doctrine is
connected another which takes a wider range. As the ultimate principium, Speusippus would
not, with Plato, recognise the Good, but, with others, who doubtless
were also Platonics, going back to the older Theologi, maintained that the primordium or
principia of the universe were to be set down, indeed, as causes of the good and perfect, but
were not the good and perfect itself, which must rather be regarded as the result of
generated existence, or development, just as the seeds of plants and animals are not the
fully formed plants or animals themselves (Arist. Met. 14.4, 5, 13.7,
12.10, Eth. Nic. 1.4; Cic. de Nat. Deor. 1.13;
Stob. Ecl. i. p. 862; Theophrast. Met. 9). The
ultimate primordium he designated, like Plato, as the absolutely one,
but would not have it to be regarded as an existing entity, since all
definitude can only be the result of development (ib. 12.7, 9.8, 14.5;
comp. Ravaisson, l.c. p. 11, &c.). When, however, with the
Pythagoreans, he reckoned the One in the series of good things (Arist. Eth. Nic. 1.4), he probably conceived it only
in its opposition to the manifold, and wished to indicate that it was from the One and not from the Manifold, that the good and
perfect is to be derived Comp. Arist. Met. 14.4, 12.10; Ravaisson, l.c. p. 15, &c.). Nevertheless Speusippus seems to have attributed
vital activity to the primordial unity, as inseparably belonging to it (Cic. de Nat. Deor. 1.13; comp. Octav. 19 ;
Arist. Metaph. 12.7 ; Ravaisson, pp. 22, &c.), probably in order to
explain how it could grow, by a process of self-development, into the good, spirit, &c.;
for spirit also he distinguished from the one, as well as from the good,
and the latter again from pleasure and pain (Stob. Ecl. Phys. i. l;
comp. Arist. Metaph. 14.4, Eth. Nic. 7.14;
Ravaisson, p. 20). Less worth notice is the attempt of Speusippus to find a more suitable
expression for the material principium, the indefinite duality of Plato (Metaph. 14.4, 5, comp. 2, 1, 13.9), and to connect the ideal numbers of Plato with
mathematical numbers (comp. Ravaisson, pp. 29, &c., 35, 38, &c., 44). With his
Pythagorizing mode of treating the doctrine of numbers we gain some acquaintance by means of
the extracts of his treatise on the Pythagorean thagorean numbers. (Theologumena Arithmetica, ed. Paris, p. 61.)