In 1930, Munch wrote to the director of Oslo's National Gallery admitting that "As for the sick child, it was the period I think of as the Age of the Pillow. A great many painters did pictures of sick children on their pillows."[11] Munch was referring to the prevalence of tuberculosis at the time; contemporary depictions of the disease can be seen in the works of Hans Heyerdahl and Christian Krohg.