with other than self-evident truths. Is it a fact that no metal is transparent? And are there any gaseous metals? These are questions of observation and experience, upon which, however, the conclusion as much depends as on the validity of the logical principle involved in the syllogism.
It would be useless to attempt in a few pages to work out even in outline an ethical system. All that can here be done is to suggest a method of going to work. Possibly, however, the respective provinces of abstract and concrete ethics may be a little more clearly indicated. What are a few of the points which only abstract ethics can decide? To begin with, we have the question: Is there any such thing as moral obligation at all ? Assuming this to be answered in the affirmative, we have the further question: Is there any one characteristic which forms the essence of all morality? Personally I believe, notwithstanding some perplexities which arise when the principle is unreservedly accepted, that such a characteristic is found in the promotion for its own sake of the happiness of some being or beings other than the agent. But here various problems present themselves. Is all self-sacrifice for the good of others more or less virtuous? Is it always positively obligatory? And if not always obligatory, where is the line to be drawn? Is there a real and absolute difference, or only a conventional and arbitrary one, between the promptings of sympathy and the dictates of justice? Is it legitimate to inflict an injury on one being in order to confer a slightly greater benefit on another? Is the happiness of every being of equal importance, e.g., of human beings and non-human, of the moral and the immoral, of those who are in suffering and those who are not? Again, in cases where interests, or what we may loosely call 'rights,' conflict, are we to calculate the course of duty on principles analogous to those which determine in mechanics the resultant of opposing forces? And when there is only a chance that such and such consequences, good or bad, will ensue, are we to treat the value of the chance as if it were a certainty?
As the mathematician, in order to arrive at the truths of pure
