6. The real state of the case is, that the principles which Art _involves_, Science alone _evolves_. The truths on which the success of Art depends, lurk in the artist's mind in an undeveloped state; guiding his hand, stimulating his invention, balancing his judgment; but not appearing in the form of enunciated Propositions. Principles are not to him direct objects of meditation: they are secret Powers of Nature, to which the forms which tenant the world owe their constancy, their movements, their changes, their luxuriant and varied growth, but which he can nowhere directly contemplate. That the creative and directive Principles which have their lodgment in the artist's mind, when _unfolded_ by our speculative powers into {134} systematic shape, become Science, is true; but it is precisely this process of _development_ which gives to them their character of Science. In practical Art, principles are unseen guides, leading us by invisible strings through paths where the end alone is looked at: it is for Science to direct and purge our vision so that these airy ties, these principles and laws, generalizations and theories, become distinct objects of vision. Many may feel the intellectual monitor, but it is only to her favourite heroes that the Goddess of Wisdom visibly reveals herself. 7. Thus Art, in its earlier stages at least, is widely different from Science, is independent of it, and is anterior to it. At a later period, no doubt, Art may borrow aid from Science; and the discoveries of the philosopher may be of great value to the manufacturer and the artist. But even then, this application forms no essential part of the science: the interest which belongs to it is not an intellectual interest. The augmentation of human power and convenience may impel or reward the physical philosopher; but the processes by which man's repasts are rendered more delicious, his journeys more rapid, his weapons more terrible, are not, therefore, Science. They may involve principles which are of the highest interest to science; but as the advantage is not practically more precious because it results from a beautiful theory, so the theoretical principle has no more conspicuous place in science because it leads to convenient practical consequences. The nature of Science is purely intellectual; Knowledge alone,--exact general Truth,--is her object; and we cannot mix with such material, as matters of the same kind, the merely Empirical maxims of Art, without introducing endless confusion into the subject, and making it impossible to attain any solid footing in our philosophy.