French mathematician and philosopher, regarded as the 'father of modern philosophy' and best known for the proposition that 'I think therefore I am' (Cogito ergo sum). Rene Descartes employed a sceptical procedure and encouraged the application of reason to human affairs. Descartes also discovered co-ordinate geometry. Although there are no records of Descartes having commented on garden design, people associate his name with the art of garden design by speaking of the 'Cartesian' garden. This is because the style of Andre Le Notre, like Rene Descartes philosophy, was founded on reason and geometry, in line with the seventeenth century enthusiasm for optics, mathematics and perspective.