India, July 11 -- In 2019, while taking a group of Delhi University students around the National Gallery of Modern Art in that city, I stopped in front of The Black Truck. This 1974 oil-on-canvas by Krishen Khanna depicts two shrouded figures sitting in the back of a truck hurtling into the night, swallowed up by black, white and grey strokes.

"How does this painting make you feel?" I asked the 20-something-year-olds. "Sad." "Empty." "Morose." "Emotionally dark," they replied.

The figures on this truck are witnesses to the times; they are the most invisibilised, the migrants who helped build India after Partition, but never benefitted from its progress. Khanna, a member of the Bombay Progressive Artists' Group, consistently documented t...