Daniel Chodowiecki, 1726–1801. Images of the Enlightenment in Berlin

Around 1767 Chodowiecki painted Jean Calas, a Toulouse merchant condemned to death, saying goodbye to his distraught family. For the first time, that painting sits in one place with its preparatory drawing, the prints made after it and the original copper plate they came from.

Calas was a Protestant, executed in 1762 on an unproven charge of strangling his own son; Voltaire's On Tolerance got him cleared three years later. You can follow the image from the oil to a test print washed in dark grey from the first plate, then to a print from the second. Around them hang red chalk portraits of Berlin's Enlightenment circle, Moses Mendelssohn and Friedrich Nicolai among them, and prints on education, family and social order.

It's a cabinet show of just over twenty works inside the Gemäldegalerie, for his 300th birthday, and no critic has reviewed it yet. Open Tuesday to Sunday, 10am to 6pm, wheelchair accessible. A public symposium runs at the Kulturforum on 14 and 15 October (registration required).