Full Idea
Some ideas belong exclusively to the mind, such as perceiving that what has been done cannot be undone, and everything else that is known by the light of nature.
Gist of Idea
We know by thought that what is done cannot be undone
Source
René Descartes (Meditations [1641], §6.82)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.160