As with all philosophers, the definition of human consciousness is of critical importance to Marx. Consciousness is how a human being defines themselves. Marx borrows from his teacher, Hegel, who argued that consciousness is a constant process called the dialectic between oppositions (thesis and antithesis). For Marx, this process is an economic one, between those with money and power and those deprived of it. This economic determinism defines history, struggle, and human consciousness.
For Marx, individual consciousness is something that cannot be divorced from one's class or social- economic group. Marx claims that all of history can be seen as a class struggle predicated on owning wealth. As a result, the consciousness of men (people) is actually the consciousness of their social grouping. Where a person is in the social- economic distinction defines how they see themselves, their nature of consciousness of self. A person who is born in the lowest of classes, according to Marx, will experience a consciousness that is closer to those of similar class distinction to them, as opposed to someone of a different, presumably higher, class. Thus, it is not an individualized and isolated consciousness of men that determines their existence and sense of self, but a social existence based on socio- economic reality that defines their consciousness, or sense of self. For Marx, history is an unfolding of this dialectic between those groups that have wealth and those who don't.