He provided the Italian historian Lodovico Guicciardini, then a resident of Flanders, with information for his history of the Low Countries entitled "Descrittione di Lodovico Guicciardini patritio fiorentino di tutti i Paesi Bassi altrimenti detti Germania inferiore" (1567; The Description of the Low Countreys). He was a correspondent of the Italian art historian Giorgio Vasari, who relied upon him for his notes about the life and works of the Liège painter Lambert Lombard. In one of his letters to Vasari, Lampsonius defended Netherlandish art against some of the disparaging remarks that Vasari had made in his "Vite". In a letter written to Vasari before the publication of the second edition of the "Vite" Lampsonius deplored the poor quality of recent prints of Italian art works, which, according to him, did not fully convey the excellence of the originals. Lampsonius suggested that Northern engravers should collaborate with Italian artists to improve this. He also asked Vasari to include in the revised edition of the "Vite" treatises on the three arts of sculpture, painting and architecture, with drawings and information about the secrets of the arts.