whether accepted or not; the conventional varies with institutions, acquiring all its force from adoption by law, and being in itself a matter of indifference prior to such adoption.  Some persons regard all Justice as thus conventional.  They say—­’What exists by nature is unchangeable, and has everywhere the same power; for example, fire burns alike in Persia and here; but we see regulations of justice often varied—­differing here and there.’  This, however, is not exactly the fact, though to a certain extent it is the fact.  Among the gods indeed, it perhaps is not the fact at all:  but among men, it is true that there exists something by nature changeable, though everything is not so.  Nevertheless, there are some things existing by nature, other things not by nature.  And we can plainly see, among those matters that admit of opposite arrangement, which of them belong to nature and which to law and convention; and the same distinction will fit in other cases also.  Thus the right hand is by nature more powerful than the left; yet it is possible that all men may become ambidextrous.  Those regulations of justice that are not by nature, but by human appointment, are not the same everywhere; nor is the political constitution everywhere the same; yet there is one political constitution only that is by nature the best everywhere (VII.).

To constitute Justice and Injustice in acts, the acts must be voluntary; there being degrees of culpability in injustice according to the intention, the premeditation, the greater or less knowledge of circumstances.  The act that a person does may perhaps be unjust; but he is not, on that account, always to be regarded as an unjust man (VIII.).

Here a question arises, Can one be injured voluntarily?  It seems not, for what a man consents to is not injury.  Nor can a person injure himself.  Injury is a relationship between two parties (IX.).  Equity does not contradict, or set aside, Justice, but is a higher and finer kind of justice, coming in where the law is too rough and general.

Book Sixth treats of Intellectual Excellences, or Virtues of the Intellect.  It thus follows out the large definition of virtue given at the outset, and repeated in detail as concerns each of the ethical or moral virtues successively.

According to the views most received at present, Morality is an affair of conscience and sentiment; little or nothing is said about estimating the full circumstances and consequences of each act, except that there is no time to calculate correctly, and that the attempt to do so is generally a pretence for evading the peremptory order of virtuous sentiment, which, if faithfully obeyed, ensures virtuous action in each particular case.  If these views be adopted, an investigation of our intellectual excellences would find no place in a treatise on Ethics.  But the theory of Aristotle is altogether different.  Though he recognizes Emotion and Intellect as inseparably implicated in