" The discipline of history is particularly important in this context because while science has had a direct impact on how historians write, and what they write about, history has itself been evolving. One of the great debates in historiography is over how events move forward. One school of thought has it that ‘great men’ are mostly what matter, that the decisions of people in power can bring about significant shifts in world events and mentalities. Others believe that economic and commercial matters force change by promoting the interests of certain classes within the overall population. In the twentieth century, the actions of Stalin and Hitler in particular would certainly seem to suggest that ‘great’ men are vital to historical events. But the second half of the century was dominated by thermonuclear weapons, and can one say that any single person, great or otherwise, was really responsible for the bomb? No. In fact, I would suggest that we are living at a time of change, a crossover time in more ways than one, when what we have viewed as the causes of social movement in the past – great men or economic factors playing on social classes – are both being superseded as the engine of social development. That new engine is science. "

― Peter Watson , The Modern Mind: An Intellectual History of the 20th Century