Katalepsis (Greek: κατάληψις, “grasping”) is a term in Stoic philosophy for a concept not far-off off from equivalent to modern comprehension. To the Stoic philosophers, katalepsis was an important premise nearly one’s state of mind as it relates to materialistic fundamental philosophical concepts, which was followed by the assent, or duty to the unadulterated thus understood.

According to the Stoics, the mind is continuously being bombarded considering impressions (phantasiai). Some of these impressions are valid and some false. Impressions are true when they are in want of fact affirmed, false if they are wrongly affirmed. Cicero relates that Zeno would illustrate katalepsis as follows:

Katalepsis was the main lessening of contention together with the Stoics and the two schools of philosophical non-belief 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 going re for the human mind and one’s methods of understanding greater meanings. To the Skeptics, all perceptions were acataleptic, i.e. bore no contract to the objects perceived, or, if they did bear any conformity, it could never be known.