And Friendship of this kind has also the pleasurable and the profitable more than that between persons unconnected by blood, in proportion as their life is also more shared in common. Then again in the Fraternal Friendship there is all that there is in that of Companions, and more in the good, and generally in those who are alike; in proportion as they are more closely tied and from their very birth have a feeling of affection for one another to begin with, and as they are more like in disposition who spring from the same stock and have grown up together and been educated alike: and besides this they have the greatest opportunities in respect of time for proving one another, and can therefore depend most securely upon the trial. Between Husband and Wife there is thought to be Friendship by a law of nature: man being by nature disposed to pair, more than to associate in Communities: in proportion as the family is prior in order of time and more absolutely necessary than the Community. And procreation is more common to him with other animals; all the other animals have Communion thus far, but human creatures cohabit not merely for the sake of procreation but also with a view to life in general::[8] because in this connection the works are immediately divided, and some belong to the man, others to the woman: thus they help one the other, putting what is peculiar to each into the common stock. And for these reasons this Friendship is thought to combine the profitable and the pleasurable: it will be also based upon virtue if they are good people; because each has goodness and they may take delight in this quality in each other. Children too are thought to be a tie: accordingly the childless sooner separate, for the children are a good common to both and anything in common is a bond of union. The question how a man is to live with his wife, or (more generally) one friend with another, appears to be no other than this, how it is just that they should: because plainly there is not the same principle of Justice between a friend and friend, as between strangers, or companions, or mere chance fellow-travellers. Chapter XIII. There are then, as was stated at the commencement of this book, three kinds of Friendship, and in each there may be friends on a footing of equality and friends in the relation of superior and inferior; we find, I mean, that people who are alike in goodness, become friends, and better with worse, and so also pleasant people; again, because of advantage people are friends, either balancing exactly their mutual profitableness or differing from one another herein. Well then, those who are equal should in right of this equality be equalised also by the degree of their Friendship and the other points, and those who are on a footing of inequality by rendering Friendship in proportion to the superiority of the other party.