Meditations on First Philosophy (subtitled In which the existence of God and the immortality of the soul are demonstrated) is a philosophical treatise written by René Descartes and first published in 1641 (in Latin). The French translation (by the Duke of Luynes with the supervision of Descartes) was published in 1647 as Méditations Metaphysiques. The original Latin title is Meditationes de prima philosophia, in qua Dei existentia et animæ immortalitas demonstratur.
The book is made up of six meditations, in which Descartes first discards all belief in things which are not absolutely certain, and then tries to establish what can be known for sure. The meditations were written as if he were meditating for 6 days: each meditation refers to the last one as "yesterday". (In fact, Descartes began work on the Meditations in 1639).
