If it is true that...

The history of all existing societies is the history of class struggles

Then it must be true that...

Freeman and slave, patrician and plebeian, lord and serf, guild-master and journeyman, stand in constant opposition to one another

If it is true that...

The history of all existing societies is the history of class struggles

Then it must be true that...

This opposition results in an uninterrupted fight that ends either in a revolutionary reconstitution of society or in the common ruin of the contending classes