 Another area in which the infinite made its appearance in 17th century geometry is in the work of Desargues (see Sakarovitch and Dhombres 1994 and Desargues 1636). Whereas in Euclidean geometry parallel lines do not meet, Desargues entertained the idea of having parallel lines meet at a point at infinity. This was a very fruitful idea that led to the development of projective geometry.