I will next advert to the applied science of Art or Aesthetics, long a barren ground, so far as scientific handling was concerned, but now a land of promise. The old thesis, "What is Beauty?" a good debating society topic, is, I hope, past contending about. The numerous influences that concur in works of art, or in natural beauty, present a fine opening for delicate analysis; at the same time, they implicate the vaguest and least advanced portion of psychology--the Emotions. The German philosophers have usually ranked aesthetics as one of the subjective sciences; but, it is only of late that the department has taken shape in their country. Lessing gave a great impulse to literary art, and originated a number of pregnant suggestions; and the German love of music has necessarily led to theories as well as to compositions. We are now in the way to that consummation of aesthetics which may be described as containing (1) a reference to psychology as the mother science, (2) a classification, comparison, and contrast of the fine arts themselves, and (3) an induction of the principles of art composition from the best examples. Anything like a thorough sifting of fine-art questions would strain psychology at every point--senses, emotions, intellect; and, if criticism is to go deep, it must ground upon psychological reasons. Now the mere artist can never be a psychologist; the art critic may, but seldom will; hence, as they will not come over to us, some of us must go over to them. The Art discussion of the greatest fountains of human feeling--love and anger--would react with advantage upon the very difficult psychology of these emotions, so long the sport of superficiality. [AESTHETICS: HEDONICS.] But I hold that aesthetics is but a corner of a larger field that is seldom even named among the sciences of mind; I mean human happiness as a whole, "eudaemonics," or "hedonics," or whatever you please to call it. That the subject is neglected, I do not affirm; but it is not cultivated in the proper place, or in the proper light-giving connection--that is to say, under the psychology of the human feelings. It should have at once a close reference to psychology, and an independent construction; while either in comprehending aesthetics, or in lying side by side with that, it would give and receive illumination. The researches now making into the laws and limits of human sensibility, if they have any value, ought to lead to the economy of pleasure and the abatement of pain. The analysis of sensation and of emotion points to this end. Whoever raises any question as to human happiness should refer it, in the first instance, to psychology; in the next, to some general scheme that would answer for a science of happiness; and, thirdly, to an induction of the facts of human experience; the three distinct appeals correcting one another. If psychology can contribute nothing to the point, it confesses to a desideratum for future inquirers.