and evil must needs derive its origin therefrom', and again in his
Physical Theses, 'for there is no other or more appropriate way of
approaching the subject of good and evil on the virtues or happiness
than from the nature of all things and the administration of the
universe--for it is to these we must attach the treatment of good and
evil inasmuch as there is no better origin to which we can refer them
and inasmuch as physical speculation is taken in solely with a view
to the distinction between good and evil.'

The last words are worth noting as showing that even with Chrysippus
who has been called the intellectual founder of Stoicism the whole
stress of the philosophy of the Porch fell upon its moral teaching.
It was a favourite metaphor with the school to compare philosophy to
a fertile vineyard or orchard. Ethic was the good fruit, physic the
tall plants, and logic the strong wall. The wall existed only to
guard the trees, and the trees only to produce the fruit. Or again
philosophy was likened to an egg of which ethic was the yolk
containing the chick, physic the white which formed its nourishment
while logic was the hard outside shell. Posidonius, a later member of
the school, objected to the metaphor from the vineyard on the ground
that the fruit and the trees and the wall were all separable whereas
the parts of philosophy were inseparable. He preferred therefore to
liken it to a living organism, logic being the bones and sinews,
physic the flesh and blood, but ethic the soul.


LOGIC

The Stoics had a tremendous reputation for logic. In this department
they were the successors or rather the supersessors of Aristotle. For