Colloquium 2 Commentary on Furley Gisela Striker When I accepted the invitation to comment on Professor Furley's paper, I did so in the hope that Stoic physics would turn out to be metaphysics after all, so that I would not get too embroiled in problems that I do not understand. My hopes were disappointed to some extent—Professor Furley has evi- dently moved away from the dim view of Stoic physics he took many years ago. This is what he wrote in 1966: " Their charac- teristic theories--ekpyrosis and the exact, predetermined repeti- tion of the cosmic cycle, their crude substitution of the active and passive kinds of matter for Aristotle's £i8os and üÀ.11. their materialistic account of qualities, their extreme pantheism, and its corollary, divination—these are unproductive digressions" (Furley, 1966). He now grants the Stoics the honor of offering "the nearest to a theory of gravity that the classical world ever came to" (p. 64). I must confess that I am not yet convinced. Rather than enter the bewildering controversy over the correct interpretation of Stoic cosmology in the terms of modern physi- cal theories, I will try to argue that the Stoic universe was held together by metaphysical, not physical bonds. I suspect that this may lend greater unity to the Stoic theory, but at the price of making it hopelessly un-scientific, at any rate from our point of view. My suspicions about the sudden appearance of something like gravitational forces in the otherwise animistic and teleological scenery of Stoic cosmology pick up a line developed by Alexander of Aphrodisias in his treatise De mixtione. This is in fact a sustained attack on the curious Stoic notion of total blend- ing (lCpâ홢J1.ç St' o홢,wv), according to which the pneuma pervades the cosmos without, so it seems, taking up any extra space. Alexander's main contention is that the pneuma is a poor materi- alist substitute for Aristotelian form, in the world at large as well as in individual bodies like organisms. I think Alexander is unquestionably right at least to the extent that it's correct to say the pneuma plays the role, in the Stoic scheme of things, that forms play in Aristotle's picture (and I take it that Prof. Furley would agree on this). For as many sources seem to show, the pneuma has two main explanatory functions: it accounts for (a) the unity of bodies or substances, and (b) the individual or char- acteristic qualities of things that make them the things they are (cf. SVF 2. 451, 452). Now in the case of what we would call inanimate bodies, this double role is described by the Stoics as a movement in two directions, both outward—this is what accounts for the qualities—and inward, accounting for the body's unity and coherence. If the universe is considered as an instance of such a unified body, then the inward or centripetal motion of the pneuma is what holds it together, while the out- ward motion presumably explains its peculiar characteristics, for example, its spherical shape. In the case of the cosmos, the inward motion is described as a general tendency of bodies or matter to move toward the center of the world, and this makes the Stoic theory of motion look like a forerunner of gravitation theory, if only in the modest sense that it describes the phenomena in the way best accounted for by the theory of gravity. Perhaps this is all that Professor Furley wanted to claim for the Stoics, and I would not wish to disagree. But it still seems to me that the general theory of the cosmic pneuma, of which the Stoic account of the unity of the cosmos purports to be an application, has less to do with physical forces and more with a metaphysics of parts and wholes. For accord- ing to the Stoics, all unified bodies, not just the elements, but also stones, plants, and animals, are held together by the same principle of inward-moving pneuma. But, as Alexander puts it (de mixt. 223, 27-32): .