Full Idea
If I suppose that everything I see is false. Nothing I remember actually existed. I have no senses, and body, shape, extension, movement and place are all chimeras. What then is true? Perhaps just the single fact that nothing is certain.
Gist of Idea
Maybe there is only one certain fact, which is that nothing is certain
Source
René Descartes (Meditations [1641], §2.24)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.102