UC Berkeley economist Brad DeLong has just published the draft of his next lecture:
Econ 115: Slouching Towards Utopia?: The Economic History of the World
in the Long Twentieth Century
You need to understand three things to grasp the state of the world
economy in 1870: that the drive to make love is one of the very strongest
of all human drives, that living standards were what we would regard as
very low for the bulk of humanity in the long trek between the invention
of agriculture in 1870, and that the rate of technological progress back
before 1870 was glacial, at best.