Commemorating the 300th Anniversary of the publication (1637) of the ground-breaking book “Discours de la Méthode” of author René Descartes (1596-1650), the French Post issued a stamp in 1937. The book described principles for philosophic and scientific methodology. Only that the stamp had the book title inscribed as “Discours sur la Méthode”. A corrected stamp was issued in consequence. The erroneous stamp was not withdrawn. The stamps were printed with 5.000.000 and 4.500.000 copies respectively. 

Left: Erroneous stamp

Right: Corrected stamp