When two partners always agree, one of them is not necessary." If there is some point you haven't thought about, be thankful if it is brought to your attention.
Dale CarnegieLooking at the other person's point of view and arousing in him an eager want for something is not to be construed as manipulating that person so that he will do something that is only for your benefit and his detriment. Each party should gain from the negotiation.
Dale Carnegie