The collective awareness of both a common material situation and a common set of interests arising out of that situation. It also entails the perception of a common enemy and is in this regard a cornerstone of what Marx, Karl referred to as class struggle. According to Marx, a class only truly becomes a class when it is conscious of its situation and acknowledges the implications of a shared identity. Class in the general sense of a group of people with common material circumstances is referred to as a class-in-itself by Marx, but once it develops consciousness and ceases to be passive with respect to its interests it becomes a class-for-itself. Marx tended to think class consciousness would occur more or less spontaneously once people had been made aware of their true situation, which is to say once the veil of false consciousness had been lifted. History does not bear this out and later theorists, such as Lenin and Mao, usually insist that class consciousness must be produced. The implication, though, is that class consciousness amounts to a willingness to take action to change the situation by revolutionary means. Again, history does not bear this out, so theorists like Hardt, Michael and Negri, Antonio have suggested that a shift in class consciousness is already a revolution and that there is no need for armed insurrection if people think differently about how they want the world to be organized.