We must begin by distinguishing between sciences and empirical fields. The empirical fields are the elementary divisions of the natural world into levels for purposes of examination. The sciences consist in the method of examining those fields, together with the presuppositions and findings of such a method. Throughout this essay, we shall consider only the empirical fields as the subject-matter of the sciences, and the way in which the sciences describe their subject-matter, but not the sciences themselves. Thus the adjective “physical” will be employed, for instance, to describe the physical empirical field, and not “physics” to describe the science.