Definition
Impermanence is the fact that everything in the external world is in flux. Possessions wear out, circumstances shift, relationships end, and every life eventually closes. Stoicism treats this not as a tragedy to deny but as a basic feature of nature to understand.
Marcus Aurelius returned often to this theme, observing that the present is all anyone truly holds and that all things are constantly being transformed into something else.
Why it matters
How it works
The Stoic responds to impermanence with two linked practices. The first is negative visualization — anticipating loss so that change, when it comes, is met with preparation rather than surprise. The second is gratitude, since what is transient is precisely what should be valued while present.
Impermanence also reinforces the dichotomy of control. Because externals are unstable by nature, staking one's peace on them is a bet against the structure of reality itself.