The foregoing remarks have already established the three main divisions of philosophy [107] which were universally acknowledged by the Stoics [108]—Logic, Natural Science, and Ethics. As regards the relative worth and sequence of these divisions, very opposite views may be deduced from the principles of the [(1) Threefold division.] Stoic teaching. There can be no doubt, and, indeed, all are agreed in allowing, that logic was subservient to the other two branches of science, being only an outpost of the system. If therefore in arranging the parts the advance is from the less important to the more important, logic will hold the first place. It will occupy the last place if the opposite mode of procedure is followed. But the relation existing between ethics and natural science is an open question. On the one hand, ethics appears to be the higher science, the crowning point of the system, the subject towards which the whole philosophical activity of the School was directed; for philosophy is practical knowledge, and its object is to lead to virtue and happiness. On the other hand, virtue and the destiny of man consist in conformity to the laws of nature, which it is the province of science to investigate. Therefore, natural science has the higher object. It lays down the universal laws which in ethics are applied to man. To it, therefore, in the graduated scale of sciences, belongs the higher rank. [(2) Relative importance of each part.] In attempting to harmonise these opposite considerations, the Stoics did not always succeed. At one time natural science is preferred to ethics, at another time ethics to natural science, [109] in the enumeration of the several branches of philosophy. In the comparisons by means of which their relations to each other were explained, [110] ethics appears at one time, at another time natural science, to be the aim and soul of the whole system. Different views were even entertained in reference to the order to be followed in teaching these sciences. [111] In describing the Stoic system, preference will be here given to that arrangement which begins with logic and goes on to natural science, ending with ethics; not only because that arrangement has among its supporters the oldest and most distinguished adherents of the Stoic School, but also because in this way the internal relation of the three parts to each other can be most clearly brought out. Allowing that, in many essential respects, natural science is modified by ethical considerations; still, in the development of the system, the chief results of science are used as principles on which ethical doctrines are founded; and logic, although introduced later than the other two branches of study, is the instrument by means of which they are put into scientific shape. If the opportunity were afforded of tracing the rise of the Stoic teaching in the mind of its founder, it would probably be possible to show how the physical and logical parts