Herein lies the key to the entire system of the Stoics, as Cleanthes’s epoch-making discovery continually received fresh applications to physics, ethics and epistemology. Other of his innovations, the outcome of his crude materialism, found less favour with his successor, who declined to follow him in identifying the primary substance with fire, or in tracing all vitality to its ultimate source in the sun, the “ruling power” of the world—a curious anticipation of scientific truth. Yet under this poetical Heraclitean mystic the school was far from flourishing. The eminent teachers of the time are said to have been Aristo, Zeno’s heterodox pupil, and Arcesilas, who in Plato’s name brought Megarian subtleties and Pyrrhonian agnosticism to bear upon the intruding doctrine; and after a vigorous upgrowth it seemed not unlikely to die out. From all danger of such a fate it was rescued by its third great teacher, Chrysippus; “but for Chrysippus there had been no Porch.”
Zeno had caught the practical spirit of his age—the desire for a popular philosophy to meet individual needs. But there was another tendency in post-Aristotelian thought—to lean upon authority and substituteChrysippus. learning for independent research—which grew stronger just in proportion as the fresh interest in the problems of the universe and the zeal for discovery declined—a shadow, we may call it, of the coming Scholasticism thrown a thousand years in advance. The representative of this tendency, Chrysippus, addressed himself to the congenial task of assimilating, developing, systematizing the doctrines bequeathed to him, and, above all, securing them in their stereotyped and final form, not simply from the assaults of the past, but, as after a long and successful career of controversy and polemical authorship he fondly hoped, from all possible attack in the future. To his personal characteristics can be traced the hair-splitting and formal pedantry which ever afterwards marked the activity of the school, the dry repellent technical procedure of the Dialecticians par excellence, as they were called. He created their formal logic and contributed much that was of value to their psychology and epistemology; but in the main his work was to new-label and new-arrange in every department, and to lavish most care and attention on the least important parts—the logical terminology and the refutation of fallacies, or, as his opponents declared, the excogitation of fallacies which even he could not refute. In his Republic Zeno had gone so far as to declare the routine education of the day (e.g. mathematics, grammar, &c.) to be of no use. Such Cynic crudity Chrysippus rightly judged to be out of keeping with the requirements of a great dogmatic school, and he laboured on all sides after thoroughness, erudition and scientific completeness. In short, Chrysippus made the Stoic system what it was, and as he left it we proceed to describe it.
And first we will inquire, What is philosophy? No idle gratification of curiosity, as Aristotle fabled of his life intellectualConception of Philosophy. (which would be but a disguise for refined pleasure), no theory divorced from practice, no pursuit of science for its own sake, but knowledge so far forth as it can be realized in virtuous action, the learning of virtue by exercise and effort and training. So absolutely is the “rare and priceless wisdom” for which we strive identical with virtue itself that the three main divisions of philosophy current at the time and accepted by Zeno—logic, physics and ethics—are defined as the most generic or comprehensive virtues. How otherwise could they claim our attention? Accordingly Aristo, holding to Cynicism when Zeno himself had got beyond it, rejected two of these parts of philosophy as useless and out of reach—a divergence which excluded him from the school, but strictly consistent with his view that ethics alone is scientific knowledge. Of the three divisions logic is the least important; ethics is the outcome of the whole, and historically the all-important vital element; but the foundations of the whole system are best discerned in the science of nature, which deals pre-eminently with the macrocosm and the microcosm, the universe and man, including natural theology and an anthropology or psychology, the latter forming the direct introduction to ethics.
The Stoic system is in brief: (a) materialism, (b) dynamic materialism, lastly (c) monism or pantheism. (a) The first of these charactersPhysics. is described by anticipation in Plato’s Sophist (246 C seq.), where, arguing with those “who drag everything down to the corporeal” (σῶμα), the Eleatic stranger would fain prove to them the existence of something incorporeal, as follows. “They admit the existence of an animate body. Is soul then something existent (oὐσία)? Yes. And the qualities of soul, as justice and wisdom—are they visible and tangible? No. Do they then exist? They are in a dilemma.” Now, however effective against Plato’s contemporary Cynics or Atomists, the reasoning is thrown away upon the Stoics, who take boldly the one horn of this dilemma. That qualities of bodies (and therefore of the corporeal soul) exist they do not deny; but they assert most uncompromisingly that they are one and all (wisdom, justice, &c.) corporeal. And they strengthen their position by taking Plato’s own definition (247 D), namely “being is that which has the power to act or be acted upon,” and turning it against him. For this is only true of Body;Materialism. action, except by contact, is inconceivable; and they reduce every form of causation to the efficient cause, which implies the communication of motion from one body to another. Again and again, therefore, only Body exists. The most real realities to Plato and Aristotle had been thought and the objects of thought, νοῦς and νοητά, whether abstracted from sensibles or inherent in “matter,” as the incognizable basis of all concrete existence. But this was too great an effort to last long. Such spiritualistic theories were nowhere really maintained after Aristotle and outside the circle of his immediate followers. The reaction came and left nothing of it all; for five centuries the dominant tone of the older and the newer schools alike was frankly materialistic. “If,” says Aristotle, “there is no other substance but the organic substances of nature, physics will be the highest of the sciences,” a conclusion which passed for axiomatic until the rise of Neoplatonism. The analogues therefore of metaphysical problems must be sought in physics; particularly that problem of the causes of things for which the Platonic idea and the Peripatetic “constitutive form” had been, each in its turn, received solutions.Tension. (b) But the doctrine that all existence is confined within the limits of the sensible universe—that there is no being save corporeal being or body—does not suffice to characterize the Stoic system; it is no less a doctrine of the Epicureans. It is the idea of tension or tonicity as the essential attribute of body, in contradistinction to passive inert matter, which is distinctively Stoic. The Epicureans leave unexplained the primary constitution and first movements of their atoms or elemental solids; chance or declination may account for them. Now, to the Stoics nothing passes unexplained; there is a reason (λόγος) for everything in nature. Everything which exists is at once capable of acting and being acted upon. In everything that exists, therefore, even the smallest particle, there are these two principles. By virtue of the passive principle the thing is susceptible of motion and modification; it is matter which determines substance (oὐσία). The active principle makes the matter a given determinate thing, characterizing and qualifying it, whence it is termed quality (ποιότης). For all that is or happens there is an immediate cause or antecedent; and as “cause” means “cause of motion,” and only body can act upon body, it follows that this antecedent cause is itself as truly corporeal as the matter upon which it acts. Thus we are led to regard the active principle “force” as everywhere coextensive with “matter,” as pervading and permeating it, and together with it occupying and filling space. This is that famous doctrine of universal permeation (κρᾶσις δι’ ὅλου), by which the axiom that two bodies cannot occupy the same space is practically denied. Thus that harmony of separate doctrines which contributes to the impressive simplicity of the Stoic physics is only attained at the cost of offending healthy common