Masculinity and femininity, selfishness and altruism, humbleness and pride, etc. The Marxist conclusion being that everything "contains two mutually incompatible and exclusive but nevertheless equally essential and indispensable parts or aspects."¹ The basic concept being that this unity of opposites in nature is the thing that makes each entity auto-dynamic and provides this constant motivation for movement and change. This idea was borrowed from Hegel who said: "Contradiction in nature is the root of all motion and of all life."