The miraculous nature of this boasted power should suffice to make us doubt whether the law is truly what it is said to be, a strict truth, quite different from the empirical concept, from the class, and from the description. In reality, the law is nothing but the empirical concept itself, the description, class or type, of which we have just spoken. In philosophy law is a synonym for the pure concept; in the empirical or natural sciences it is a synonym for the empirical concept; hence laws are sometimes called _empirical_ laws, or laws of experience. If they were not empirical, they would not be naturalistic, but philosophic universals, which, as we have seen, are unfruitful in the field of the natural sciences. The law of the wolf is the empirical concept of the wolf: granted that in reality there is found one part of the representation corresponding to that concept, it is possible to conclude that the rest is also found. Thus Cuvier (to choose a very trite example), arranging the types of animals and hence the laws of the correlations of organs, was able to reconstruct from one surviving bone the complete fossil animal. In like manner, granted the chemical concept of water, H2O, and given so much of oxygen and double that quantity of hydrogen, O and H2, and submitting the two bodies to the other conditions established by chemistry, it is possible to conclude that water will be seen to appear. All naturalistic laws are of this type. Certain naturalists and theorists have reasonably protested against the division of the natural sciences into descriptive and explicative, sciences of classification and sciences of laws, and have maintained that all have one common character, namely, law. But this is not because the law is superior to the class or to the empirical concept, but because the two things are identical: the law is the empirical concept and the empirical concept is the law. [Sidenote: _The postulate of the uniformity of nature, and its meaning._]