Katalepsis (Greek: κατάληψις, “grasping”) is a term in Stoic philosophy for a concept in bill to equivalent to modern comprehension. To the Stoic philosophers, katalepsis was an important premise with reference to one’s divulge of mind as it relates to greedy fundamental philosophical concepts, which was followed by the assent, or commitment to the resolution thus understood.

According to the Stoics, the mind is permanently being bombarded subsequent to impressions (phantasiai). Some of these impressions are legitimate and some false. Impressions are legitimate when they are in reality affirmed, false if they are wrongly affirmed. Cicero relates that Zeno would illustrate katalepsis as follows:

Katalepsis was the main tapering off of contention amid the Stoics and the two schools of philosophical incredulity during the Hellenistic period: the Pyrrhonists and the Academic Skeptics of Plato’s Academy. These Skeptics, who chose the Stoics as their natural philosophical opposites, eschewed much of what the Stoics believed roughly the human mind and one’s methods of covenant greater meanings. To the Skeptics, all perceptions were acataleptic, i.e. bore no harmony to the objects perceived, or, if they did bear any conformity, it could never be known.