The idea that humans are naturally greedy and selfish and that "you can't change human nature" is often used to explain the atrocities that happen in the world. From imperialist wars, to racism, to mass poverty the barbarism in society can be seen everywhere.
But we also see the huge potential for humans to overcome seemingly permanent divisions. A glimpse of this was visible during the 18-day occupation of Tahrir Square in February 2011 when Muslim and Christian Egyptians protected each other during prayer. Through collective struggle against a common enemy their divisions fell into the background.
For Karl Marx, humans are both shaped by the society in which we live and play an active role in shaping the world. Under capitalism workers are compelled to sell their labour power to those that own and control the means of production.
The exploitation and divisions that this leads to shape the whole of society.
It was in The Economic and Philosophic Manuscripts that Marx first showed how workers are "alienated" from their own labour under capitalism and the impact this has on our lives and our relationships with other human beings.
Written in 1844, The Economic and Philosophic Manuscripts is one of Marx's earliest works. In it the young Marx broke from the highly influential German philosopher Hegel. Hegel saw alienation as a purely intellectual phenomenon - seeing the world in a mistaken way.
But Marx identified the key feature of all human societies as conscious, collective labour on the world around us to meet our needs. Under capitalism this fundamental feature of our nature - our "species-being" as Marx calls it - is no longer under our control. This has a number of consequences.
First, workers lose control over the products of their labour. Marx writes, "the object that labour produces, its product, confronts it as an alien being, as a power independent."
Workers have no control over what happens to the products of their labour - they become the property of the capitalist to sell on the market for profit:
"The worker cannot use the things he produces to keep alive or to engage in further productive activity... The worker's needs, no matter how desperate, do not give him a licence to lay hands on what these same hands have produced, for all his products are the property of another."
Take the example of a worker on an assembly line making parts for Apple iPhones. You cannot live on iPhone parts, it is unlikely you will ever see the finished iPhone and you probably won't be able to afford to buy an iPhone. Instead, in exchange for labour, we get a lump sum of money, a wage, to purchase commodities produced by other workers' alienated labour.
Second, just as the product of labour is separate from us, so too is control over the process of labour itself.
As Marx puts it, "labour is exterior to the worker... Therefore he [the worker] does not confirm himself in his work, but denies himself, feels miserable instead of happy, deploys no free physical and intellectual energy, but mortifies his body and ruins his mind."
From the hours that we have to work, the techniques we use, the health and safety of our workplace, every minute of our working lives is regulated in some way and out of our control.
This is true for all workers, whether you work in a call centre, a supermarket, a factory or a school (and increasingly face endless targets and Ofsted inspections).
Third, Marx shows that, because the object of work is separated from those who create it, and the process of labour is out of workers' control, it follows that workers' relationships with others are also alienated:
"An immediate consequence of man's alienation from the product of his work, his vital activity and his species-being, is the alienation of man from man."
We see this in the immense stress which work puts on us, leading to anxiety, stress and depression and the pressures this puts on our relationships.
It also creates a feeling of powerlessness among workers - that the world of capitalism is beyond their control and is dominated by the impersonal logic of the market rather than being created by workers' own labour.
In the Manuscripts, Marx is still in the process of developing his understanding of capitalism as a system based on exploitation and conflict.
But the ideas at the centre of the Manuscripts are central to a Marxist understanding of the world.
The fight for a classless society, free of alienated labour, oppression and imperialist wars, can only be achieved through collective struggle by the working class to reclaim control over their own labour. The key to ending alienation lies in an end to the system that creates it.