"In June 1816 I was traveling in the company of my friend Erhardt for the second time on the Danube to Vienna " Johann Adam Klein wrote in his autobiography. His Portrait of the Nuremberg painter Mathias Christoph Hartmann must therefore have been developed at Vienna immediately before Klein's departure. The journal documents the connection between the two prior to 1818, when Hartmann was included in the Nuremberg association of artists and art lovers, in which the one year older Klein was already an honorary member (since 1815).

For many years, Klein portrayed his friends and fellow artists, always in lead, with a steady hand and a delicate lineament, and almost always in profile...