“We humans are terrible animals.” Sebastião Salgado works with silver and light. In partnership with his wife Lélia, the acclaimed artist has spent four decades documenting humanity producing extraordinary duotone photographs.

They're not simply black-and-white, they're something altogether different, more tangible, alive. Through his work, the former economics student has witnessed some of the most significant events on our planet, events that drove him to the brink of despair. His son Juliano began to document his father's work which in turn, was documented by Oscar nominated filmmaker Wim Wenders (Buena Vista Social Club). Theirs is an unusual, compelling and at times electrifying collaboration.

The Salt Of The Earth opens with an apocalyptic vision, a photograph that shows thousands of men crawling across the tortured landscape of an open cut mine in Brazil; an image that speaks to the philosophy of the artist's entire body of work. As if they were 'building the tower of Babel', it represents 'all of mankind since the dawn of time' says Salgado. It is the first of many introductions to his work that is both thrilling and frightening. 'People,' he says, 'are the salt of the earth' and it was those who were unable to tell their own story that captured his attention.

Shaped by political movements of the 1960's, he and Lélia set out to document the world. Framed thematically and driven by an empathy for the human condition, his work took him around the world to photograph tribespeople in Papua and Brazil, refugees in Ethiopia and Rwanda, impoverished workers of the industrial age. His compilations stand as testament to the couple's interests with titles like Sahel, End of the World; Exodus and Workers. Until recently, they were linked by observations which were nothing if not heartbreaking – genocide in Mali, starvation in Ethiopia, the destruction of Kuwait's oil fields. Now he tells Wenders that we, as a species, 'have no right to live'. He had seen into the heart of darkness.

Wenders doesn't shy from taking us to the edge either. There is a moment in this film when you'd be quite happy for it to end so unrelenting are these portraits of the chaos and despair of human activity. As Salgado shares his stories about each photograph, the suffering he describes is truly distressing. Fortunately for us, for the film and for Salgado, the photographer found a glimmer of hope and was guided back from the precipice. Not only is it a relief for the viewers' now battered souls, but his rebirth offers hope when all seemed hopeless, and it comes from a most unexpected corner. The development energised the exhausted artist and gave rise to a new book, Genesis, a love letter to the planet.

Throughout, The Salt Of The Earth is composed as if Salgado himself, not Wenders, was behind the camera. Often that is the case as, with weapons poised, the two photographers are seen ready to shoot each another. Together they've created a film of immense beauty and significance. It is like being immersed in an intoxicating pool of talent that leaves you dazed, overwhelmed and enriched all at once. It is not an experience you'll take lightly, nor is it one you should miss.

// COLIN FRASER

Previewed at The Reel Room, Sydney, on 26 March 2015