text: "There are two reasons why we go astray: either there is in the soul an evil quality which has been brought about by wrong opinions, or, even if not possessed by false ideas, the soul is prone to falsehood and rapidly corrupted by some outward appearance which attracts it in the wrong direction. For this reason it is our duty either to treat carefully the diseased mind and free it from faults, or to take possession of the mind when it is still unoccupied and yet inclined to what is evil. Both these results can be attained by the main doctrines of philosophy; therefore the giving of such precepts is of no use. Besides, if we give forth precepts to each individual, the task is stupendous. For one class of advice should be given to the financier, another to the farmer, another to the business man, another to one who cultivates the good graces of royalty, another to him who will seek the friendship of his equals, another to him who will court those of lower rank. In the case of marriage, you will advise one person how he should conduct himself with a wife who before her marriage was a maiden, and another how he should behave with a woman who had previously been wedded to another; how the husband of a rich woman should act, or another man with a dowerless spouse. Or do you not think that there is some difference between a barren woman and one who bears children, between one advanced in years and a mere girl, between a mother and a step-mother? We cannot include all the types, and yet each type requires separate treatment; but the laws of philosophy are concise and are binding in all cases. Moreover, the precepts of wisdom should be definite and certain: when things cannot be defined, they are outside the sphere of wisdom; for wisdom knows the proper limits of things.