Covey explains that this habit is all about multiplying what different individuals could do.
He calls this creative cooperation and the way he puts it is that the creative cooperation could create a force greater that the sum of the parts.
Effective synergy relies on communication, many people make synergy impossible by reacting from scripts, they do not listen, reflect and respond, instead they react reflexively.
Cooperation and communication are the two legs of a synergistic relationship. If sincere cooperation and communication are lacking the power of synergy will be lost. 2+2 = 5.