Full Idea
I now seem able to posit as a general rule that everything I very clearly and distinctly perceive is true.
Gist of Idea
My general rule is that everything that I perceive clearly and distinctly is true
Source
René Descartes (Meditations [1641], §3.35)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.113