For somehow every one is by nature prone to that which is likest to himself, and in this way the whole city becomes unequal in property and in disposition; and hence there arise in most states the very results which we least desire to happen.

Now, to add to the law an express provision, not only that the rich man shall not marry into the rich family, nor the powerful into the family of the powerful, but that the slower natures shall be compelled to enter into marriage with the quicker, and the quicker with the slower, may awaken anger as well as laughter in the minds of many; for there is a difficulty in perceiving that the city ought to be well mingled like a cup, in which the maddening wine is hot and fiery, but when chastened by a soberer God, receives a fair associate and becomes an excellent and temperate drink (compare Statesman).

Yet in marriage no one is able to see that the same result occurs.

Wherefore also the law must let alone such matters, but we should try to charm the spirits of men into believing the equability of their children's disposition to be of more importance than equality in excessive fortune when they marry; and him who is too desirous of making a rich marriage we should endeavour to turn aside by reproaches, not, however, by any compulsion of written law.
Let this then be our exhortation concerning marriage, and let us remember what was said before--that a man should cling to immortality, and leave behind him children's children to be the servants of God in his place for ever.

All this and much more may be truly said by way of prelude about the duty of marriage.