of the nature of fire, or of a warm
breath, (Cic. Tusc. Quaest. i. 9; de Nat. Deor. iii. 4,) and therefore as
mortal.

In ethics he agreed with the Cynics in recognising the constitutional
nature of moral obligations, though he differed from them with respect to
things indifferent, and opposed their morose contempt for custom, though
he did not allow that the gratification of mere external wants, or that
external good fortune, had any intrinsic value. He comprised everything
which could make life happy in virtue alone (Cic. Acad. i. 10), and called
it the only good which deserved to be striven after and praised for its
own sake (Cic. de Fin. iii. 6, 8), and taught that the attainment of it
must inevitably produce happiness. But as virtue could, according to his
system, only subsist in conjunction with the perfect dominion of reason,
and vice only in the renunciation of the authority of reason, he inferred
that one good action could not be more virtuous than another, and that a
person who had one virtue had all, and that he who was destitute of one
was destitute of all.

_Cleanthes_ was born at Assos in the Troas, about 300 B.C.; he came to
Athens at an early age, and became the pupil of Zeno, whom at his death he
succeeded in his school. He differed from his master in regarding the soul
as immortal, and approximated to the Cynics in denying that pleasure was
agreeable to nature, or in any respect good. He died of voluntary
starvation at the age of eighty.

_Chrysippus_ was born B.C. 280, at Soli in Cilicia. He came at an early
age to Athens, and became a pupil of Cleanthes; and among the later Stoics
he was more regarded than either Zeno or Cleanthes. He died B.C. 207.

His doctrines do not appear to have differed from those of Zeno; only
that, from feeling the dangerous influence of the Epicurean principles, he
endeavoured to popularize the Stoic ethics.

_Epicurus_ was an Athenian of the Attic demos Gargettus, whence he is
sometimes simply called the Gargettian. He was, however, born at Samos,
B.C. 342, and did not come to Athens till the age of eighteen, when he
found Xenocrates at the head of the Academy, and by some authors is said
to have become his pupil, though he himself would not admit it (Cic. de
Nat. Deor. i. 26). At the outbreak of the Samian war he crossed over to
Colophon, where he collected a school. It is said that the first thing
that excited him to the study of philosophy was the perusal of the wo