"The history of all hitherto existing society is the history of class struggle." So begins the Communist Manifesto, written by Karl Marx and Frederick Engels.
Rather than trying to make society conform to a timeless ideal, or to discover some fixed ‘human nature’, Marxists see society as a process, evolving through stages of development, driven forward by the struggle between the exploiters and the exploited.
Ultimately, it is not morality or our ideas that determine the structure and dynamics of society, but economic conditions.
Importantly, as Fiona explains, by studying the past we can understand how to bring about a socialist future.