plow," better harnesses for horses to pull the plow, and a three-field crop rotation scheme. In the third part of the book, he examined medieval machines that converted motion and energy. The most notable was the compound crank. The work elicited over 30 reviews, many of which were hostile. P. H. Sawyer and R. H. Hilton wrote the most scathing of the early reviews, beginning with: "Technical determinism in historical studies has often been combined with adventurous speculations particularly attractive to those who like to have complex developments explained by simple causes. The technical determinism of Professor Lynn White Jr., however, is peculiar in that, instead of building new and provocative theories about general historical development on the basis of technical studies, he gives a misleadingly adventurist cast to old-fashioned platitudes by supporting them with a chain of obscure and dubious deductions from scanty evidence about the progress of technology." Nevertheless, the book remains in print and still stands as a seminal work in the field. The historical roots of present-day ecologic crisis In 1967, White conjectured that the Christian influences in the Middle Ages were at the root of ecological crisis in the 20th century. He gave a lecture on December 26, 1966, titled, "The Historical Roots of Our Ecologic Crisis" at the Washington meeting of the AAAS, that was later published in the journal Science. White's article was based on the premise that "all forms of life modify their context", i.e. every living organism in some way alters its environment or habitat. He believed man's relationship with the natural environment was always a dynamic and interactive one, even in the Middle Ages, but marked the Industrial Revolution as a fundamental turning point in our ecological history. He suggests that at this point the hypotheses of science were married to the possibilities of technology and our ability to destroy and exploit the environment was vastly increased. Nevertheless, he also suggests that the mentality of the Industrial Revolution, that the earth was a resource for human consumption, was much older than the actuality of machinery, and has its roots in medieval Christianity and attitudes towards nature. He suggests that "what people do about their ecology depends on what they think about themselves in relation to things around them." Citing the Genesis creation story he argued that Judeo-Christian theology had swept away pagan animism and normalized exploitation of the natural world