The Picnic, Extremadura, Spain 1998. Photograph: Harry Gruyaert/Magnum Photos

If you were telling the history of photography through the Magnum agency you might compare Henri Cartier-Bresson’s famous pictures of families picnicking on the banks of the River Marne, taken in 1938, with this image by Harry Gruyaert, of families eating in the sunshine in Extremadura, Spain in 1998. Cartier-Bresson set the black-and-white documentary tone of the agency he co-founded for several decades. His picnickers had a belt-and-braces solidity, apparently timeless working men and women on their Sunday off. His camera gave them gravitas and a sort of idealised humanity. In Gruyaert’s picture the social history of the families themselves seems of little interest; his eye is entirely for the play of light and colour. He might take his inspiration from Gerard Manley Hopkins: “Glory be to God for dappled things!”