The Cataleptic Impression

The grasping impression

For the Stoics knowledge begins from the kataleptic or “grasping” impression — a phantasia that arises from a real object, exactly copies it, and could come from nothing else, so that it all but seizes the mind and drags it to assent. It is their criterion of truth, the secure foothold between opinion and full knowledge. The skeptics of the Academy attacked it relentlessly, denying that any impression carries such a guarantee.