Term used by Descartes to signify the particular transparent quality of ideas on which we are entitled to rely, even when indulging the method of doubt. The nature of this quality is not itself made out clearly and distinctly in Descartes, but there is some reason to see it as characterizing those ideas that we we just cannot imagine false, and must therefore accept on that account, rather than ideas that have any more intimate, guaranteed, connection with the truth.