Scorsese's films are a tough watch - but deeply moral.

'It's three and a half hours long,' said a friend. 'I think I'll give it a miss.'

We were talking about the new Martin Scorsese movie, 'Killers of The Flower Moon', which came out a few weeks ago. The epic running time might have put off quite a few potential audience members, but I wanted to see the film, which focuses on a series of murders that took place in the 1920s in the Osage nation in Oklahoma. The Osage were a tribe of Native Americans who had been shunted around America by the bossy white man. When oil was discovered on their land, the Osage became very wealthy, with lifestyles that included cars and white servants. The film shows a series of murders that took place as family members, including white men, tried to get at the money.

Scorsese's oeuvre has always been dry-eyed about human imperfection, with films such as Taxi Driver, Raging Bull and Goodfellas showing all manner of darkness. The new film is similarly uncompromising. It's a tough watch. I closed my eyes at times, as one killing follows another. It's a grim depiction of what humans are capable of - our venality, our selfishness, our rapacious greed. I found it unsettling and disturbing.

While Scorsese's films are unabashed in their depiction of brutality, they can be a sometimes be confusing. Goodfellas, which I watched again recently, is disturbing because it comes perilously close to depicting brutal, selfish men with a sheen of glamour. Some viewers have struggled to see the nuance in Scorsese's films. In 1981, John Hinckley Jr sought to impress Jodie Foster by shooting President Reagan. It turned out Hinckley had been watching Taxi Driver.

Although Scorsese's recent films are not easy viewing, they carry a profound moral message. His last film, The Irishman, a sort of companion piece to Killers Of The Flower Moon, also showed the appalling depths that humans will go to in search of money and power. In both films, the glossy sheen of Goodfellas is missing, and a stronger sense of justice prevails, as the killers eventually become more and more isolated and lonely. The last twenty minutes of The Irishman are devastating as we see the main character, Frank Sheeran, played by Robert De Niro, grow older and more lonely, abandoned by those close to him, confronted by his terrible past.

We have a responsibility to live well, Scorsese is saying quietly in his recent films. Otherwise, our lives can slide towards something hollow, demented and cruel. 'In the absence of compassion there is cancer,' sang Bruce Cockburn on the song Night Train, from his 1997 album The Charity of Light. It's important that we live mindfully, trying to be kind, aware of others, and conscious of our own venality, our own potential weakness, our capacity for self-centredness. The worst of us is never far away, but (thankfully), the best of us is also close to the surface.

Miles Salter is a writer and musician based in York, UK. You can drop him

a line at [email protected] and follow him on Twitter @MilesWrites.