For ordinary purposes probably it is well not to seek to understand it. Acquaintance with the structure of the eye does not help seeing. To determine beforehand just how polite we should be would not facilitate human intercourse. And possibly a completed scheme of goodness would rather confuse than ease our daily actions. Science does not readily connect with life. For most of us all the time, and for all of us most of the time, instinct is the better prompter. But if we mean to be ethical students and to examine conduct scientifically, we must evidently at the outset come face to face with the meaning of goodness. I am consequently often surprised on looking into a treatise on ethics to find no definition of goodness proposed. The author assumes that everybody knows what goodness is, and that his own business is merely to point out under what conditions it may be had. But few readers do know what goodness is. One suspects that frequently the authors of these treatises themselves do not, and that a hazy condition of mind on this central subject is the cause of much loose talk afterwards. At any rate, I feel sure that nothing can more justly be demanded of a writer on ethics at the beginning of his undertaking than that he should attempt to unravel the subtleties of this all-important conception. Having already in a previous volume marked out the Field of Ethics, I believe I cannot wisely go on discussing the science that I love, until I have made clear what meaning I everywhere attach to the obscure and familiar word _good_. This word being the ethical writer's chief tool, both he and his readers must learn its construction before they proceed to use it. To the study of that curious nature I dedicate this volume. II To those who join in the investigation I cannot promise hours of ease. The task is an arduous one, calling for critical discernment and a kind of disinterested delight in studying the high intricacies of our personal structure. My readers must follow me with care, and indeed do much of the work themselves, I being but a guide. For my purpose is not so much to impart as to reveal. Wishing merely to make people aware of what has always been in their minds, I think at the end of my book I shall be able to say, "These readers of mine know now no more than they did at, the beginning." Yet if I say that, I hope to be able to add, "but they see vastly more significance in it than they once did, and henceforth will find the world interesting in a degree they never knew before." In attaining this new interest they will have experienced too that highest of human pleasures,--the joy of clear, continuous, and energetic thinking. Few human beings are so inert that they are not ready to look into the dark places of their minds if, by doing so, they can throw light on obscurities there.