(4) Finally, a study of ethics should help us to see what are the prevalent sins and moral dangers of our day, and thus arouse us to put the weight of our blame and praise where they are needed. Widespread public opinion is a force of incalculable power, which is largely unused. Politics and business, and to a far greater extent than now private life, will become clean and honest and kind just so soon as a sufficient number of people wake up and demand it. We have the power to make sins which are now generally tolerated and respectable, so odious, so infamous, that they will practically disappear. There are certain of the older forms of sin which the race in its long struggle upward has so effectually blacklisted that only a few perverts now lapse into them; we have execrated out of existence whole classes of cruelty and vice. But with the changing and ever more complex relations of society new forms of sin continually creep in; these we have not yet come to brand with the odium they deserve. Leaders of society and pillars of the church are often, and usually without disturbance of conscience, guilty of wrongdoing as grave in its effects, or graver, than many of the faults we relentlessly chastise. On the other hand, many really useful reforms are blocked because they awaken old prejudices or cross silly and meaningless conventions. The air is full of proposals, invectives, causes, movements; how shall we know which to espouse and which to reject, or where best to lend a hand? We need a consistent and well-founded point of view from which to judge. To get such a sane and far-sighted moral perspective; to see the acts of our fellow men with a proper valuation; to be able to point out the insidious dangers of conduct which is not yet as generally rebuked as it ought to be; and at the same time to emancipate ourselves and others from the mistaken and merely arbitrary precepts that are intermingled with our genuine morality, and so attain the largest possible freedom of action, such should be the outcome of a thorough study of ethical principles and ideals. PART I THE EVOLUTION OF MORALITY CHAPTER I THE ORIGIN OP PERSONAL MORALITY