Luca Cambiaso, The Artist Painting His Father, 104 x 97 cm, oil on canvas, early 1570s (Palazzo Bianco, Genoa, Italy). An interesting play on the popular "artist painting his self-portrait" and "artist looking in a mirror" compositions, this double portrait stresses the similarities between the two men, thus also making it a meditation on ageing and a poignant memento mori. A cropped version of this is in Vasari Corridor, Uffizi Gallery, Florence.
"The Stone Breakers," Gustave Courbet (Lost) Painted in 1849, this classic example of social realism was hailed for its unsentimental depiction of poor laborers, one young and one old, removing rocks from a roadside. Inspired by a chance meeting with two downtrodden workers, Courbet deliberately broke with convention by capturing the men in gritty detail. In 1945, the painting was destroyed during an Allied bombing near the city of Dresden, Germany.