The term science is used to cover three separate categories, to which throughout this paper we shall give three separate names. There is (1) the field in which science operates. This is the external world of natural phenomena, partly uniform and partly chance. There is (2) the science itself. This is the laboratory of instruments, techniques, operations, the method by which the field is studied. Finally, there is (3) the laws. This is the level of abstractions, of causal laws or of statistical probability averages, invariant or approaching invariance, mathematically expressed. The three, of course, belong together. Science carries the activity; it studies the field to find the laws.