266 H. M. STANLEY : a thorough following out of his principles would bring discordant classifications ; that the order of dependence, for instance, is very complex, and far different from that of historic development. We would add, further, that the form of the order of historic develop- ment is ramifying, and not linear as Comte "supposed. As Comte made an advance on all previous classifiers in adopt- ing clearly defined and scientific principles of classification, so Mr. Spencer made an advance upon him in classifying, not by many principles, but by a single principle, that of increasing con- creteness. Prof. Bain justly criticises his scheme as too revolu- tionary and far-fetched, as well as lacking in exactness. Chauncey Wright criticises it as merely adding useless terms for divisions of the sciences already recognised by a proper nomenclature. The Abstract, Abstract-Concrete, and Concrete Sciences of Mr. Spencer are, in his view, simply equivalent to the old distinctions of Formal, Mixed, and Material Sciences. There is one thought with reference to the plans of Comte and Mr. Spencer which is of interest and which we will note here, and that is the relation of their principles of classification to certain educational principles or laws of mental growth. Mr. Spencer exhibits an order from abstract to concrete, and the well recognised order of intellectual growth is the reverse, from con- crete to abstract. Comte's classification claims to represent the order from simple to complex, and from general to special, and the order of mental growth is the first as stated, and the second reversed. We should expect that the order of individual mental progress would fairly represent the order of the progress of the race in the sciences, but this is plainly not the case. Mathe- matics, for instance, the earliest of the sciences in developing, dealt with the most simple but with the most general and ab- stract of notions. Its rapid progress was due in great measure to progress according to the law of least mental resistance. It was easier for the mind to work out an ideal world of form, than to patiently make inductions among the complexities and per- plexities of the actual world of tnings. Without commenting further on the classifications of Comte and Mr. Spencer, let us approach the subject for independent study from a logical point of view. In treating any subject we assume that it is the first work to define the subject, to attain a clear idea of the material with which we are to deal. In forming a classification of the sciences it is a preliminary step of prime importance to decide what departments of know- ledge are to be considered as sciences. What is a science ? For lack of a clear understanding with reference to this fundamental question there has been much confusion, since even accurate writers use the term science in radically different meanings. Some claim that Political Economy is not yet a science, and many assert that it is. Different writers, having different con- ceptions of what constitutes a science, have assigned different
