The reader who recalls certain passages in First Principles, in the Principles of Biology, and in the Principles of Psychology, will perceive above a re-statement, in another form, of generalizations set forth in those works. Especially will he be reminded of the proposition that Life is the definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external coexistences and sequences; and still more of that abridged and less specific formula, in which Life is said to be the continuous adjustment of internal relations to external relations. (§7 ¶1)

The presentation of the facts here made, differs from the presentations before made, mainly by ignoring the inner part of the correspondence and attending exclusively to that outer part constituted of visible actions. But the two are in harmony; and the reader who wishes further to prepare himself for dealing with our present topic from the evolution point of view, may advantageously join to the foregoing more special aspect of the phenomena, the more general aspects before delineated. (§7 ¶2)

After this passing remark, I recur to the main proposition set forth in these two chapters, which has, I think, been fully justified. Guided by the truth that as the conduct with which Ethics deals is part of conduct at large, conduct at large must be generally understood before this part can be specially understood; and guided by the further truth that to understand conduct at large we must understand the evolution of conduct; we have been led to see that Ethics has for its subject-matter, that form which universal conduct assumes during the last stages of its evolution. We have also concluded that these last stages in the evolution of conduct are those displayed by the highest type of being, when he is forced, by increase of numbers, to live more and more in presence of his fellows. And there has followed the corollary that conduct gains ethical sanction in proportion as the activities, becoming less and less militant and more and more industrial, are such as do not necessitate mutual injury or hindrance, but consist with, and are furthered by, co-operation and mutual aid. (§7 ¶3)

These implications of the Evolution-Hypothesis, we shall now see harmonize with the leading moral ideas men have otherwise reached. (§7 ¶4)