France (1937 SG574) 300th Anniversary of Publication of 'Discourse de la 
                                     mèthode' wrongly scripted as 'Discourse sur la 
                                     mèthode'.
France (1937 SG575) Corrected stamp.
Monaco (1996 SG2282) Renè Descartes and optical diagram.

Descartes (1596-1650) was a French philosopher, mathematician as well as a scientist. He formulated optical 
laws for refraction and showed accommodation was caused by changes in the shape of the lens. He also 
described unconscious reflex action. In his treatise Des passions de l'âme (1649), he noted a feigned blow to 
the eyes caused a blink. His most famous is 'Discourse de la mèthode' which is a philosophical treatise containing
the famous statement 'I think, therefore, I am'. The book also contains many analytical geometry.