The big picture: Rene Burri's shadows of doubt

There seem to be two distinct ways of looking at René Burri’s Men on a Rooftop, a defining picture by the renowned Magnum photographer, taken in São Paulo in 1960. One views it as a supreme exercise in composition, like an abstract painting: the photograph is divided into three vertical sections – road, buildings and rooftop – each delineated by contrasts in sunlight and shadow. The image is a photographic equivalent of the modernist architecture it celebrates, dwelling on concrete geometries.

In the other way of seeing, the eye fixes on the four figures on the roof. The cityscape below and its teeming traffic becomes a vertiginous backdrop to their curious, elongated silhouettes. The four are cast in an apparently conspiratorial drama that demands to be understood. What is their purpose up there? Why are three of the figures in step behind the man ahead? The shot looks like a still from a film – but the tone is elusive.

Speaking about the photograph – a highlight of a forthcoming Magnum print sale – not long before he died in 2014, Burri described how it came about. “Did I know those men were there when I took that photograph? No. Buildings weren’t guarded in those days. It was a question of getting to the top and knocking on the door… ‘Yeah, yeah, yeah. Come in!’ So I walked out on to the terrace and, at that moment, those guys came from nowhere and I shot five images.”

For him, more than anything else, the picture simply represented a professional coming of age. “In those days Henri Cartier-Bresson [the president of Magnum] limited us to lenses from 35mm to 90mm. When I showed him the photos he said: ‘Brilliant René!’ The lens I used was 180 mm – I never told him! At that point I broke loose from my mentor. I killed my mentor!”

Turning Points, Magnum’s square print sale, in collaboration with The Everyday Projects, runs from Monday 6 April at 9am EST to Sunday 12 April at 6pm EST. Signed or estate-stamped, museum-quality, 6x6in prints from more than 100 visual artists will be available for $100 (£80) each