Except our own thoughts, there is nothing absolutely in our power.

Taken at face value, the sentence draws a sharp boundary between what is genuinely controllable and what is not: external events, other people, and even many outcomes of our own actions remain contingent, while our thoughts (judgments, intentions, assent) are the one domain that can be fully governed. The idea aligns with a long Stoic tradition—especially Epictetus’s distinction between what depends on us and what does not—recast in a rationalist key often associated with Descartes’s emphasis on the mind’s autonomy. As a maxim, it encourages intellectual discipline: if certainty and freedom are to be found anywhere, they begin with regulating belief and directing attention rather than attempting to master fortune.