Tractatus duo

and name, but sycophancy and flattery are certainly the truest plague and corruption of all true friendship: which, although it puts on the appearance of great affection, nevertheless utterly infringes upon the powers of friendship and adulterates its nature. For a sycophant mimics the words of a friend, but not his mind, not his sincere love and affection.

Furthermore, all these things of which we have spoken must be mutual: since friends not only try to return mutual services, but also strive to surpass one another in doing good, and even to anticipate one another, as much as lies in their power. Therefore, those manifestations of love, consensus, and protection are reciprocal: not that a friend confers a benefit in the hope of a reward or of recovering a benefit (since no pious person has mercenary charity toward his neighbor) but because the power and nature of friendship itself does not allow things to happen otherwise than for them to be mutual and reciprocal. For that love which is named Friendship is, as I have said, mutual and reciprocal, and of the number of those things which are said to be aretē virtue. Therefore, all those duties are mutually performed, received, and returned, although (and this must be diligently noted) they are not always equal and the same. For often one receives more from the other than he can confer upon him, whether because of the difference in the status and condition of the friends, or the difference in their wealth. For one perhaps will be very rich, the other poor: one fortunate, the other calamitous: one an exile, the other a native. But nevertheless, he to whom lesser and fewer things are available, even if he does not perhaps confer as much as he receives, still repays and confers as much as he possibly can. From which it happens that duties among friends are always indeed mutual, yet not always equal and the same: since not even the affection itself is always equal and the same among them, as appears in Jonathan and David 1 Samuel 20:41.