We may, indeed, according to our personal sympathies, prefer one type of creature to another. We may love the martial, or the angelic, or the political temperament. We may delight to find in others that balance of susceptibilities and enthusiasms which we feel in our own breast. But no moral precept can require one species or individual to change its nature in order to resemble another, since such a requirement can have no power or authority over those on whom we would impose it. All that morality can require is the inward harmony of each life: and if we still abhor the thought of a possible being who should be happy without love, or knowledge, or beauty, the aversion we feel is not moral but instinctive, not rational but human. What revolts us is not the want of excellence in that other creature, but his want of affinity to ourselves. Could we survey the whole universe, we might indeed assign to each species a moral dignity proportionate to its general beneficence and inward wealth; but such an absolute standard, if it exists, is incommunicable to us; and we are reduced to judging of the excellence of every nature by its relation to the human. All these matters, however, belong to the sphere of ethics, nor should we give them here even a passing notice, but for the influence which moral ideas exert over aesthetic judgments. Our sense of practical benefit not only determines the moral value of beauty, but sometimes even its existence as an aesthetic good. Especially in the right _selection_ of effects, these considerations have weight. Forms in themselves pleasing may become disagreeable when the practical interests then uppermost in the mind cannot, without violence, yield a place to them. Thus too much eloquence in a diplomatic document, or in a familiar letter, or in a prayer, is an offence not only against practical sense, but also against taste. The occasion has tuned us to a certain key of sentiment, and deprived us of the power to respond to other stimuli.