The error consists in looking for the explanation of social phenomena in the most general laws. This is natural within certain limits, but has been pushed to extreme, but logical consequences, by the American, Carey (_Social Science_). He looks, in effect, to one of the oldest sciences, and one, consequently, relating to the most highly general phenomena, those of astronomy, for the universal laws of society. Geometry, he holds, gives us principles equally valid for the chemist, the sociologist, and for him who measures the earth. A system assuming to explain complex phenomena solely by the laws of phenomena more simple, may be compared to the effort to give an account of a book, not by reading it line by line, but by examining the cover and the title-page. As DeGreef elsewhere puts it, there is a hierarchy in science, proceeding from the more general to the less general, depending on the nature of the phenomena studied. This hierarchy has been variously stated. Comte puts it thus: mathematics, astronomy, physics, chemistry, physiology, social physics (sociology). Baldwin,[101] writing much later, of course, puts it thus:-- So here, as elsewhere, there is a gradation, a hierarchy, in science: chemistry necessary to life, but not itself of life; forces in the environment necessary to evolution, but not themselves vital; life-processes necessary to consciousness, but not themselves mental; consciousness necessary to society, but not all consciousness social; social consciousness necessary to social organization, but not all social consciousness actually in a social organization.