And in this deliberation three reasons assisted me.

One of them was self-love, which is the source of all the rest, as every one sees.

For there is no more lawful nor more courteous way of doing honour to one's self than by doing honour to one's friend; and, since friendship cannot exist between the unlike, wherever one sees friendship, likeness is understood; and wherever likeness is understood, thither runs public praise or blame.

And from this reason two great lessons may be learnt: the one is, never to wish that any vicious man should seem your friend, for in that case a bad opinion is formed of him who has made the evil man his friend; the other is, that no one ought to blame his friend publicly, because, if you consider well the aforesaid reason, he but points to himself with his finger in his eye.
The second reason was the desire for the duration of this friendship; wherefore it is to be known, as the Philosopher says in the ninth book of the Ethics, in the friendship of persons of unequal position it is requisite, for the preservation of that friendship, for a certain proportion to exist between them, which may reduce the dissimilarity to a similarity, as between the master and the servant.

For, although the servant cannot render the same benefit to the master that is conferred on him, yet he ought to render the best that he can, with so much solicitude and freewill that that which is dissimilar in itself may become similar through the evidence of good-will, which proves the friendship, confirms and preserves it.