Vitae philosophorum

spring as the right temperature of the air consequent upon his approach to us; summer as the heating of the air above the earth when he travels to the north; while autumn they attribute to the receding of the sun from us. As for the winds, they are streams of air, differently named[*](The lacuna of the mss. can be filled from the parallel passage of Aetius, Diels, Doxographi Graeci, p. 374 a 23.) according to the localities from which they blow. And the cause of their production is the sun through the evaporation of the clouds. The rainbow is explained as the reflection of the sun’s rays from watery clouds or, as Posidonius says in his Meteorology, an image of a segment of the sun or moon in a cloud suffused with dew, which is hollow and visible without intermission, the image showing itself as if in a mirror in the form of a circular arch. Comets, bearded stars, and meteors are fires which arise when dense air is carried up to the region of aether.

A shooting star is the sudden kindling of a mass of fire in rapid motion through the air, which leaves a trail behind it presenting an appearance of length. Rain is the transformation of cloud into water, when moisture drawn up by the sun from land or sea has been only partially evaporated. If this is cooled down, it is called hoar-frost. Hail is frozen cloud, crumbled by a wind; while snow is moist matter from a cloud which has congealed: so Posidonius in the eighth book of his Physical Discourse. Lightning is a kindling of clouds from being rubbed together or being rent by wind, as Zeno says in his treatise On the Whole; thunder the noise these clouds make when they rub against each other or burst.

Thunderbolt is the term used when the fire is

They maintain that the parts of the world are arranged thus. The earth is in the middle answering to a centre; next comes the water, which is shaped like a sphere all round it, concentric with the earth, so that the earth is in water. After the water comes a spherical layer of air. There are five celestial circles: first, the arctic circle, which is always visible; second, the summer tropic; third, the circle of the equinox; fourth, the winter tropic; and fifth, the antarctic, which is invisible to us. They are called parallel, because they do not incline towards one another; yet they are described round the same centre.[*](The κέντρον is rather an axis (namely, a diameter of the celestial sphere) than a point.) The zodiac is an oblique circle, as it crosses the parallel circles.

And there are five terrestrial zones: first, the northern zone which is beyond the arctic circle, uninhabitable because of the cold; second, a temperate zone; a third, uninhabitable because of great heats, called the torrid zone; fourth, a counter-temperate zone; fifth, the southern zone, uninhabitable because of its cold.

Nature in their view is an artistically working fire, going on its way to create; which is equivalent to a fiery, creative, or fashioning breath. And the soul is a nature capable of perception. And they regard it as the breath of life, congenital with us; from which they infer first that it is a body and secondly that it survives death. Yet it is perishable, though the soul of the universe, of which the individual souls of animals are parts, is indestructible.

Zeno of Citium and Antipater, in their treatises De anima, and Posidonius define the soul as a warm breath; for by this we become animate and this enables us to move. Cleanthes indeed holds that all souls continue to exist until the general conflagration; but Chrysippus says that only the souls of the wise do so.[*](Cf. Aet. Plac. iv. 19. 4 (Arnim, ii. p. 140).)

They count eight parts of the soul: the five senses, the generative power in us, our power of speech, and that of reasoning. They hold that we see when the light between the visual organ and the object stretches in the form of a cone: so Chrysippus in the second book of his Physics and Apollodorus. The apex of the cone in the air is at the eye, the base at the object seen. Thus the thing seen is reported to us by the medium of the air stretching out towards it, as if by a stick.

We hear when the air between the sonant body and the organ of hearing suffers concussion, a vibration which spreads spherically and then forms waves and strikes upon the ears, just as the water in a reservoir forms wavy circles when a stone is thrown into it. Sleep is caused, they say, by the slackening of the tension in our senses, which affects the ruling part of

Semen is by them defined as that which is capable of generating offspring like the parent. And the human semen which is emitted by a human parent in a moist vehicle is mingled with parts of the soul, blended in the same ratio in which they are present in the parent.

Chrysippus in the second book of his Physics declares it to be in substance identical with vital breath or spirit. This, he thinks, can be seen from the seeds cast into the earth, which, if kept till they are old, do not germinate, plainly because their fertility has evaporated. Sphaerus and his followers also maintain that semen derives its origin from the whole of the body; at all events every part of the body can be reproduced from it. That of the female is according to them sterile, being, as Sphaerus says, without tension, scanty, and watery. By ruling part of the soul is meant that which is most truly soul proper, in which arise presentations and impulses and from which issues rational speech. And it has its seat in the heart.

Such is the summary of their Physics which I have deemed adequate, my aim being to preserve a due proportion in my work. But the points on which certain of the Stoics differed from the rest are the following.