Sextus Empiricus Pyrrhoniae Hypotyposes 3.25.242

[242] And herein, too, the procedure of the Stoics, in presenting the notion of the apprehensive impression, is logically unsound; for in stating, on the one hand, that an apprehensive impression is that which is derived from a real object, ¹ and, on the other hand, that a real object is that which is capable of giving rise to an apprehensive impression, they fall into the fallacy of circular reasoning. If, then, in order that an art of living may exist, there must first exist art, and in order that art may subsist apprehension must pre-exist, and in order that apprehension may subsist assent to an apprehensive impression must be apprehended, but the apprehensive impression is indiscoverable, —then the art of living is indiscoverable.