XVII. But in some of these causes there is a uniform operation, and in others there is not. In nature and in art there is uniformity; but in the others there is none. But still of those causes which are not uniform, some are evident, others are concealed. Those are evident which touch the desire or judgment of the mind; those are concealed which are subject to fortune: for as nothing is done without some cause, this very obscure cause, which works in a concealed manner, is the issue of fortune. Again, these results which are produced are partly unintended, partly intentional. Those are unintended which are produced by necessity; those are intentional which are produced by design. But those results which are produced by fortune are either unintended or intentional. For to shoot an arrow is an act of intention; to hit a man whom you did not mean to hit is the result of fortune. And this is the topic which you use like a battering-ram in your forensic pleadings; if a weapon has flown from the man's hand rather than been thrown by him. Also agitation of mind may be divided into absence of knowledge and absence of intention. And although they are to a certain extent voluntary, (for they are diverted from their course by reproof or by admonition,) still they are liable to such emotions that even those acts of theirs which are intentional sometimes seem either unavoidable, or at all events unintentional.

The whole topic of these causes then being now fully explained, from their differences there is derived a great abundance of arguments in all the important discussions of orators and philosophers. And in the cases which you lawyers argue, if there is not so plentiful a stock, what there are, are perhaps more subtle and shrewd. For in private actions the decisions in the most important cases appear to me to depend a great deal on the acuteness of the lawyers. For they are constantly present, and are taken into counsel; and they supply weapons to able advocates whenever they have recourse to their professional wisdom.

In all those judicial proceedings then, in which the words "according to good faith" are added, or even those words, "as ought to be done by one good man to another;" and above all, in all cases of arbitration respecting matrimonial rights, in which the words "juster and better" occur, the lawyers ought to be always ready. For they know what "dishonest fraud," or "good faith," or "just," or "good" mean. They are acquainted with the law between partners; they know what the man who has the management of the affairs of another is bound to do with respect to him whose affairs he manages; they have laid down rules to show what the man who has committed a charge to another, and what he who has had it committed to him, ought to do; what a husband ought to confer on his wife, and a wife on her husband. It will, therefore, when they have by diligence arrived at a proper understanding of the topics from which the necessary arguments are derived, be in the power not only of orators and philosophers, but of lawyers also, to discuss with abundance of argument all the questions which can arise for their consideration.

XVIII. Conjoined to this topic of causes is that topic which is supplied by causes. For as cause indicates effect, so what has been effected points out what the efficient cause has been. This topic ordinarily supplies to orators and poets, and often to philosophers also, that is to say, to those who have an elegant and argumentative and rich style of eloquence, a wonderful store of arguments, when they predict what will result from each circumstance. For the knowledge of causes produces a knowledge of effects.

The remaining topic is that of comparison, the genus and instances of which have been already explained, as they have in the case of the other topics. At present we must explain the manner of dealing with this one. Those things then are compared which are greater than one another, or less than one another, or equal to one another. In which these points are regarded; number, appearance, power, and some particular relation to some particular thing.

Things will be compared in number thus: so that more advantages may be preferred to fewer; fewer evils to more; more lasting advantages to those which are more short-lived; those which have an extensive application to those the effect of which is narrowed: those from which still further advantages may be derived, and those which many people may imitate and reproduce.

Things again will be compared with reference to their appearance, so that those things may be preferred which are to be desired for their own sake, to those which are only sought for the sake of something else: and so that innate and inherent advantages may be preferred to acquired and adventitious ones; complete good to mixed good; pleasant things to things less pleasant; honourable things to such as are merely useful; easy things to difficult ones; necessary to unnecessary things; one's own advantage to that of others; rare things to common ones; desirable things to those which you can easily do without; things complete to things which are only begun; wholes to parts; things proceeding on reason to things void of reason; voluntary to necessary things; animate to inanimate things; things natural to things not natural; things skilfully produced by art to things with which art has no connexion.

But power in a comparison is perceived in this way: an efficient cause is more important than one which effects nothing; those causes which can act by themselves are superior to those which stand in need of the aid of others; those which are in our power are preferable to those which are in the power of another; lasting causes surpass those which are uncertain; things of which no one can deprive us are better than things which can be easily taken away.

But the way in which people or things are disposed towards some things is of this sort: the interests of the chief citizens are more important than those of the rest: and also, those things which are more agreeable, which are approved of by more people, or which are praised by the most virtuous men, are preferable. And as in a comparison these things are the better, so those which are contrary to them are the worse.

But the comparison between things like or equal to each other has no elation or submission; for it is on equal terms: but there are many things which are compared on account of their very equality; which are usually concluded in this manner: "If to assist one's fellow-citizens with counsel and personal aid deserves equal praise, those men who act as counsellors ought to enjoy an equal glory with those who are the actual defenders of a state." But the first premiss is certainly the case; therefore so must the consequent be.