Therefore, although nothing has commonly been less attractive than treatises on beauty or less a guide to taste than disquisitions upon it, we may yet hope for some not merely theoretical gain from these studies. They have remained so often without practical influence because they have been pursued under unfavourable conditions. The writers have generally been audacious metaphysicians and somewhat incompetent critics; they have represented general and obscure principles, suggested by other parts of their philosophy, as the conditions of artistic excellence and the essence of beauty. But if the inquiry is kept close to the facts of feeling, we may hope that the resulting theory may have a clarifying effect on the experience on which it is based. That is, after all, the use of theory. If when a theory is bad it narrows our capacity for observation and makes all appreciation vicarious and formal, when it is good it reacts favourably upon our powers, guides the attention to what is really capable of affording entertainment, and increases, by force of new analogies, the range of our interests. Speculation is an evil if it imposes a foreign organization on our mental life; it is a good if it only brings to light, and makes more perfect by training, the organization already inherent in it. We shall therefore study human sensibility itself and our actual feelings about beauty, and we shall look for no deeper, unconscious causes of our aesthetic consciousness. Such value as belongs to metaphysical derivations of the nature of the beautiful, comes to them not because they explain our primary feelings, which they cannot do, but because they express, and in fact constitute, some of our later appreciations. There is no explanation, for instance, in calling beauty an adumbration of divine attributes. Such a relation, if it were actual, would not help us at all to understand why the symbols of divinity pleased. But in certain moments of contemplation, when much emotional experience lies behind us, and we have reached very general ideas both of nature and of life, our delight in any particular object may consist in nothing but the thought that this object is a manifestation of universal principles. The blue sky may come to please chiefly because it seems the image of a serene conscience, or of the eternal youth and purity of nature after a thousand partial corruptions. But this expressiveness of the sky is due to certain qualities of the sensation, which bind it to all things happy and pure, and, in a mind in which the essence of purity and happiness is embodied in an idea of God, bind it also to that idea.