Definition
Impressions and assent name the two stages of the Stoic theory of mind. An impression is the appearance that arises unbidden. Assent is the act by which the mind accepts that appearance as true, rejects it, or suspends judgment.
The impression cannot be prevented; it simply occurs. Assent, however, is voluntary. This is why the Stoics located human freedom precisely in the moment of assent — it is the point where reason can intervene.
Why it matters
How it works
When an impression arrives — for example, that an event is a disaster — the Stoic does not assent automatically. They test the embedded judgment: is the event truly bad, or merely an external? If the judgment fails the test, assent is withheld and the impression loses its grip.
This is the practical core of the discipline of assent. Repeated over time, the brief pause between appearance and acceptance becomes habitual, and the mind grows steadier.