The essay question is:Drawing on Marx’s theory of class, discuss the view that power relations in society are fundamentally economic in character. I'm stuck on how to define a power relation, I've never read Marx talk about power as a thing in itself, I just understand his view on class struggle and I'm hypothesizing the notion that the economic dominance he pointed out can be seen as a power relation, in fact the main source of power, in Marxist terms.
What I'm asking is if Marx ever did talk about power as a thing in itself, just to help me define power relation in this essay.