In the case of each of the moral qualities or dispositions that have been discussed, as with all the other virtues also, there is a certain mark to aim at, on which the man who knows the principle involved fixes his gaze, and increases or relaxes the tension1 accordingly; there is a certain standard determining those modes of observing the mean which we define as lying between excess and defect, being in conformity with the right principle. 1. [2] This bare statement however, although true, is not at all enlightening. In all departments of human endeavor that have been reduced to a science, it is true to say that effort ought to be exerted and relaxed neither too much nor too little, but to the medium amount, and as the right principle decides. Yet a person knowing this truth will be no wiser than before: for example, he will not know what medicines to take merely from being told to take everything that medical science or a medical expert would prescribe. 1. [3] Hence with respect to the qualities of the soul also, it is not enough merely to have established the truth of the above formula; we also have to define exactly what the right principle is, and what is the standard that determines it.2 1. [4]
Now we have divided the Virtues of the Soul into two groups,