In this passage Mr. Spencer propounds morality or ethics as a matter for scientific study, only to be understood or explained as part of general conduct when it is capable of explanation deductively from antecedent causes. The distinction recognised between conduct called moral and conduct regarded as immoral is only to be understood when, after a historical survey of human actions and of the actions of organisms in general, we not only perceive its immediately antecedent causes, but, going behind them, recognise the ultimate necessity of their occurrence in the very nature of the universe. This reveals the special features of Mr. Spencer's method in the treatment of his subject as distinguished from that followed by Mr. Leslie Stephen in his "Science of Ethics," a distinction which we may conveniently mark by terming them respectively the Philosophic and the Scientific methods. The former term we use in the sense assigned to it in the definition given by Mr. Spencer in "First Principles."[4] A philosophy is complete when the mind has been able to form for itself such an appraisement of the relations and conditions of factors at a period sufficiently remote to ante-date any great amount of complexity as will enable us deductively to frame a history of developments which may correspond with the actual history of sequences in the concrete universe. If this appraisement of a remote cosmos characterised by comparative simplicity nevertheless admits the existence of many factors whose differences are not accounted for, philosophy is so far formally incomplete: but as the determination of these points lies beyond the powers of human reason, philosophy may justly be regarded as practically complete if it unifies from this point of view all the knowledge with which the human mind is conversant. If we are able to include all the sciences in one coherent whole nothing more can be expected of philosophy--beyond that lies the realm of speculation and the Unknowable. The scope of the sciences is not so ambitious. Their aim is limited within a much narrower purview. They seek merely to ascertain the laws which subsume special classes of phenomena. They recognise causation and their inductions are valid to the extent of the classes of facts expressed in any particular law. But each science or class of facts is severally and separately worked upon even though the progress of study is ever disclosing the mutual dependence of the various sciences.