Little more can be said concerning the opinions of a sect whose fundamental maxim was that nothing could be known, and nothing should be taught. It lay midway between the other philosophies; and in the altercations of the various schools it was at once attacked by all,[168] yet appealed to by each of the contending parties, if not to countenance its own sentiments, at least to condemn those advocated by its opponents,[169] and thus to perform the office of an umpire.[170] From this necessity, then, of being prepared on all sides for attack,[171] it became as much a school of rhetoric as of philosophy,[172] and was celebrated among the ancients for the eloquence of its masters.[173] Hence also its reputation was continually varying: for, requiring the aid of great abilities to maintain its exalted and arduous post, it alternately rose and fell in estimation, according to the talents of the individual who happened to fill the chair.[174] And hence the frequent alterations which took place in its philosophical tenets; which, depending rather on the arbitrary determinations of its present head, than on the tradition of settled maxims, were accommodated to the views of each successive master, according as he hoped by sophistry or concession to overcome the repugnance which the mind ever will feel to the doctrines of universal scepticism. And in these continual changes it is pleasing to observe that the interests of virtue and good order were uniformly promoted; interests to which the Academic doctrines were certainly hostile, if not necessarily fatal. Thus, although we find Carneades, in conformity to the plan adopted by Arcesilas,[175] opposing the _dogmatic_ principles of the Stoics concerning moral duty,[176] and studiously concealing his private views even from his friends;[177] yet, by allowing that the suspense of judgment was not always a duty, that the wise man might sometimes _believe_ though he could not _know_;[178] he in some measure restored the authority of those great instincts of our nature which his predecessor appears to have discarded. Clitomachus pursued his steps by innovations in the same direction;[179] Philo, who followed next, attempting to reconcile his tenets with those of the Platonic school,[180] has been accounted the founder of a fourth academy--while, to his successor Antiochus, who embraced the doctrines of the Porch,[181] and maintained the fidelity of the senses, it has been usual to assign the establishment of a fifth. 7.