Diogo de Carvalho e Sampayo

Diogo de Carvalho e Sampayo (28 May 1750 – 29 December 1807) He graduated from the University of Coimbra where he studied Law, later, in 1783, serving as a judge in Viana do Castelo. He resigned from his post after a conflict with the administrative authorities of the nearby town of Vila do Conde. Johann Wolfgang von Goethe was familiar with Carvalho e Sampayo's work: his seminal treatise Theory of Colours (published 1810) includes a general assessment of Sampayo's 1791 book Memória sobre a Formação Natural das Cores ("An Essay on the Natural Formation of Colours").

Starting in 1789, he moved to Madrid where he headed the Portuguese diplomatic representation there, first as chargé d'affaires, then as a minister plenipotentiary, and finally as ambassador extraordinary, returning definitely to Portugal in 1801. In Madrid, Carvalho e Sampayo made acquaintance with Wilhelm von Humboldt.