Science is a social function, a particular type of social function, just as circulation or digestion is a function of the body. Science and its results are the basis of our civilization, just as the steel girders in a modern building are the basis of the building. All sorts of things are being done by science to improve building and make it more efficient, healthy, and comfortable; and yet these efforts are often frustrated by old specifications and by-laws, and for economic reasons. There are some who find in science the evil genius of to-day, and who would like to see scientific research given a holiday, or even to see a return to a more medieval state of affairs. It was the theological system in the Middle Ages which was responsible, and in the case of ancient Greece it was the economic fact that the industrial application of science was not necessary because the economic system was based on slavery.