Freeman and slave, patrician and plebeian, lord and serf, guild master and journeyman, in a word, oppressor and oppressed, stood in constant opposition of each other, carried on an uninterrupted, now hidden, now open fight, a fight that each time ended in a revolutionary reconstitution of society at large, or in the common ruin of the contending classes. Karl Marx's Communist Party Manifesto is an example of inductive thinking deductive thinking