On such matters, however, generalisations have little value, as exceptions are very numerous. Differences of character, age, experience, and judgment, and countless special circumstances, will modify the family type, and it is in discovering these differences that wisdom in marriage mainly consists. The directions in which married life may influence character are also very many; but in the large number of cases in which it brings with it a great weight of household cares and family interests it will usually be found with both partners, but especially with the woman, at once to strengthen and to narrow unselfishness. She will live very little for herself, but very exclusively for her family. On the intellectual side such marriages usually give a sounder judgment and a wider knowledge of the world rather than purely intellectual tastes. It is a good thing when the education which precedes marriage not only prepares for the duties of the married life, but also furnishes a fair share of the interests and tastes which that state will probably tend to weaken. The hard battle of life, and the anxieties and sorrows that a family seldom fails to bring, will naturally give an increased depth and seriousness to character. There are, however, natures which, though they may be tainted by no grave vice, are so incurably frivolous that even this education will fail to influence them. As Emerson says, 'A fly is as untameable as a hyæna.' The age that is most suited for marriage is also a matter which will depend largely on individual circumstances. The ancients, as is well known, placed it, in the case of the man, far back, and they desired a great difference of age between the man and the woman. Plato assigned between thirty and thirty-five, and Aristotle thirty-seven, as the best age for a man to marry, while they would have the girls married at eighteen or twenty.[71] In their view, however, marriage was looked upon very exclusively from the side of the man and of the State. They looked on it mainly as the means of producing healthy citizens, and it was in their eyes almost wholly dissociated from the passion of love. Montaigne, in one of his essays, has expounded this view with the frankest cynicism.[72] Yet few things are so important in marriage as that the man should bring into it the freshness and the purity of an untried nature, and that the early poetry and enthusiasm of life should at least in some degree blend with the married state. Nor is it desirable that a relation in which the formation of habits plays so large a part should be deferred until character has lost its flexibility, and until habits have been irretrievably hardened.