The culture of any society is usually thought to be of two kinds: material and nonmaterial. Material culture includes the man-made phenomena which have physical properties such as height, breadth, and weight. A boat, a machine, a house — all these objects are part of the material culture. The nonmaterial culture is that portion of the environment which surrounds man and which has an impact on his behavior but which lacks these material properties: values, beliefs, traditions, and all the other habits and ideas invented and acquired by man as a member of society. Contemporary sociological theory tends to assign primary importance to the nonmaterial culture in choosing problems for study. It assumes, for example, that boats, planes, automobiles, and so forth, are not nearly so important as the traditions we have developed which make their manufacture possible — indeed, which prescribe how we are to use them. The emphasis of contemporary sociology is to insist that the material culture would not exist had not the nonmaterial culture first been available to suggest the ideas which are embodied in the inventions of material culture.