Full Idea
Possible existence is a perfection in the idea of a triangle, just as necessary existence is a perfection in the idea of God.
Gist of Idea
Possible existence is a perfection in the idea of a triangle
Source
René Descartes (Reply to Fifth Objections [1641], 383)
Book Reference
Descartes,René: 'Meditations on First Philosophy etc.', ed/tr. Cottingham,John [CUP 1986], p.97