The social organism, like the individual, may be healthy or diseased. Health and disease are very difficult things to define accurately: but for practical purposes, there are certain states about which no mistake can be made. When we have even a very imperfect catalogue and description of states that are clearly and certainly diseases, we may form a rough preliminary definition of health by saying that it means the absence of all these states. Now the health of society involves among other things, that right is done by the individuals composing it. And certain social diseases consist in a wrong direction of the conscience. Hence the determination of abstract right depends on the study of healthy and diseased states of society. How much light can be got for this end from the historical records we possess? A very great deal, if, as I believe, for ethical purposes the nature of man and of society may be taken as approximately constant during the few thousand years of which we have distinct records. The matters of fact on which rational ethic must be founded are the laws of modification of character, and the evidence of history as to those kinds of character which have most aided the improvement of the race. For although the moral sense is intuitive, it must for the future be directed by our conscious discovery of the tribal purpose which it serves. II. RIGHT AND WRONG: THE SCIENTIFIC GROUND OF THEIR DISTINCTION. [1] The questions which are here to be considered are especially and peculiarly everybody's questions. It is not everybody's business to be an engineer, or a doctor, or a carpenter, or a soldier; but it is everybody's business to be a citizen. The doctrines and precepts which guide the practice of the good engineer are of interest to him who uses them and to those whose business it is to investigate them by mechanical science; the rest of us neither obey nor disobey them. But the doctrines and precepts of morality, which guide the practice of the good citizen, are of interest to all; they must be either obeyed or disobeyed by every human being who is not hopelessly and forever separated from the rest of mankind. No one can say, therefore, that in this inquiry we are not minding our own business, that we are meddling with other men's affairs. We are in fact studying the principles of our profession, so far as we are able; a necessary thing for every man who wishes to do good work in it.