Note 15 — Chapter V · LOGIC OF THE STOICS.

Whether this enquiry was pursued by the older Stoics in all its comprehensiveness is a point on which we have no information. Boëthus, whose views on this subject were attacked by Chrysippus, had assumed the existence of several standards, such as Reason, Perception, Desire, Knowledge. Others, in the vaguest manner, had spoken of Right Reason (ὀρθὸς λόγος) as being the standard of truth.15 Hence it may be inferred that before the time of Chrysippus the Stoics had no distinctly developed theory of knowledge. Nevertheless there are expressions of Zeno and Cleanthes still extant which prove that the essential parts of the later theory were already held by these philosophers,16 although it is no doubt true that it first received that scientific form in which alone it is known to us at the hands of Chrysippus.