It will, however, be discussed sufficiently, if it is rendered perspicuous according to its subject matter. For accuracy must not be similarly investigated in all discussions, as neither in all the works of art. Things beautiful, however, and just, with which the political science is conversant, possess so great a difference, and are involved in so much ambiguity, that (to some persons) their subsistence appears to be from law only, and not from nature. What is good, likewise, possesses a certain ambiguity of this kind, because it happens that many persons are injured by it. For some have perished through wealth, but others through fortitude. We must be satisfied, therefore, in speaking about and from such things, if we can indicate the truth by a rude adumbration, and if our conclusions in discussing things which have a frequency of subsistence are similar in accuracy to the things themselves. After the same manner, likewise, it is requisite to admit every thing that has been said. For it is the province of an erudite man so far to investigate the accurate in each genus of things, as the nature of the thing will admit; since it appears to be a similar thing to assent to a mathematician (mathematika) when speaking probably, and to require demonstrations from a rhetorician (rhetorike). Every one, however, judges well of those things which he knows, and of these is a good judge. Hence, the man who is learned in any thing, judges well of that thing; but he in short forms a proper judgment about every thing, who is learned in every thing. Hence, a youth is not a proper auditor of the political science, for he is unskilled in the actions pertaining to life. But reasonings are from and about these. And besides this, if he yields to his passions, he will in vain, and without any advantage, be an auditor (of ethical doctrines;) since the end here is not knowledge (gnosis), but action (praxis). It makes, however, no difference whether a person is a youth as to his age, or has juvenile manners. For the defect is not from time, but from living, and engaging in every pursuit from passion (pathos); since the knowledge of such persons, in the same manner as that of the intemperate, is useless. But a knowledge of these things will, be very advantageous to those whose appetites and actions are conformable to reason. And thus much by way of preface concerning the auditor (of ethics,) how he ought to admit (discussions of this kind,) and what we propose (to consider in this treatise.)