Erasmus of Rotterdam was one of the leading humanists of his time and corresponded with numerous fellow-humanists throughout Europe. More than 3,000 of his letters have survived. In his manual on letter-writing, Opus de conscribendis epistolis, he mentions thirty different types of letter.
Hans Holbein the Younger (1497–1543), Bildnis des schreibenden Erasmus von Rotterdam, 1523, location of the original: Kunstmuseum Basel; source: Hans Holbein le jeune: L'œuvre du maitre, Paris, Librairie Hachette & Cie., 1912.