G. S. September, 1906. INTRODUCTION The sense of beauty has a more important place in life than aesthetic theory has ever taken in philosophy. The plastic arts, with poetry and music, are the most conspicuous monuments of this human interest, because they appeal only to contemplation, and yet have attracted to their service, in all civilized ages, an amount of effort, genius, and honour, little inferior to that given to industry, war, or religion. The fine arts, however, where aesthetic feeling appears almost pure, are by no means the only sphere in which men show their susceptibility to beauty. In all products of human industry we notice the keenness with which the eye is attracted to the mere appearance of things: great sacrifices of time and labour are made to it in the most vulgar manufactures; nor does man select his dwelling, his clothes, or his companions without reference to their effect on his aesthetic senses. Of late we have even learned that the forms of many animals are due to the survival by sexual selection of the colours and forms most attractive to the eye. There must therefore be in our nature a very radical and wide-spread tendency to observe beauty, and to value it. No account of the principles of the mind can be at all adequate that passes over so conspicuous a faculty. That aesthetic theory has received so little attention from the world is not due to the unimportance of the subject of which it treats, but rather to lack of an adequate motive for speculating upon it, and to the small success of the occasional efforts to deal with it. Absolute curiosity, and love of comprehension for its own sake, are not passions we have much leisure to indulge: they require not only freedom from affairs but, what is more rare, freedom from prepossessions and from the hatred of all ideas that do not make for the habitual goal of our thought. Now, what has chiefly maintained such speculation as the world has seen has been either theological passion or practical use. All we find, for example, written about beauty may be divided into two groups: that group of writings in which philosophers have interpreted aesthetic facts in the light of their metaphysical principles, and made of their theory of taste a corollary or footnote to their systems; and that group in which artists and critics have ventured into philosophic ground, by generalizing somewhat the maxims of the craft or the comments of the sensitive observer. A treatment of the subject at once direct and theoretic has been very rare: the problems of nature and morals have attracted the reasoners, and the description and creation of beauty have absorbed the artists; between the two reflection upon aesthetic experience has remained abortive or incoherent.