What is the criterion here? Who is to judge? How are we to know what is the proper mean in any matter? Mathematical analogies will not help us. It is not a case of drawing a straight line from one extreme to the other, and finding the middle point by bisection. And Aristotle refuses to lay down any rule of thumb in the matter. There is no golden rule by virtue of which we can tell where the proper mean is. It all depends on circumstances, and on the person involved. What is the proper mean in one case is not the proper mean in another. What is moderate for one man is immoderate for his neighbour. Hence the matter must be left to the good judgment of the individual. A sort of fine tact, good sense, is required to know the mean, which Aristotle calls "insight." This insight is both the cause and the {319} effect of virtue. It is the cause, because he who has it knows what he ought to do. It is the effect, because it is only developed by practice. Virtue renders virtue easy. Each time a man, by use of his insight, rightly decides upon the mean, it becomes easier for him to discriminate next time. Aristotle attempts no systematic classification of the virtues, as Plato had done. This sort of schematism is contrary to the practical character of his thought. He sees that life is far too complex to be treated in this way. The proper mean is different in every different case, and therefore there are as many virtues as there are circumstances in life. His list of virtues, therefore, is not intended to be exhaustive. It is merely illustrative. Though the number of virtues is infinite, there are certain well-recognized kinds of good action, which are of such constant importance in life that they have received names. By the example of some of these virtues Aristotle illustrates his doctrine of the mean. For instance, courage is the mean between cowardice and rashness. That is to say, cowardice is the defect of boldness, rashness the excess, courage the reasonable medium. Munificence is the mean between pettiness and vulgar profusion, good temper between spiritlessness and irascibility, politeness between rudeness and obsequiousness, modesty between shamelessness and bashfulness, temperance between insensibility and intemperance.