31. Let us in general consider the actions and reactions produced in the universe either by nature or by art. In the works of nature, there is an action of the whole on the parts, of the parts on the whole, and of the parts on the parts. In the works of art, art either alone accomplishes what it has undertaken, or depends on natural forces to effect certain natural operations. We may call actions of the universe, all that the total circular expanse affects on itself or its part. For in fact, the heavens by moving themselves, somehow effect themselves and their parts, both those in its own revolutions, or on the earth. The mutual reactions and passions of the parts of the universe are easy to recognize, such as the positions taken up by the sun, and the influence the sun exercises on the other stars, and especially in regard to the earth; further, the processes in its own elements, as well as in those of the other constellations, and of objects on earth--all of which deserve separate consideration. MOST OF THE ARTS ACHIEVE THEIR OWN ENDS. Architecture and the fine arts, fulfil themselves in such an object. Medicine, agriculture and similar professions, however, are auxiliary arts, and obey the laws of nature, assisting their efficient production so as to make them as natural as possible. As to rhetoric, music, and other arts of refinement, which serve the education of souls in improving or degrading men, it remains an open question how many there are of them, and what power they possess. In all these things, we will have to examine what may be of use to us for the questions we are treating, and we will have to discover the cause of the facts, as far as possible. ABSURDITY OF PTOLEMEAN ASTROLOGY.