Articulating values provides everyone with guiding lights, ways of choosing among competing priorities and guidelines about how people will work together. For example, a media-literacy group may envision a nation where every child knows how to talk back to television. Vision is the most powerful motivator in an organization. If it's vivid and meaningful enough, people can do astounding things to bring it to realization. But if it's lacking, no amount of resources will be able to get people off their butts.
Most people can relate to a personal vision, their personal values, their mission in life.
But when two or more people agree to work together, the difficulties of arriving at such articulations multiply. When you want to bring new people in, you must give them ways to participate in the vision of the organization. Everyone's preferences and abilities must be taken into account for a group to work together optimally. What this means practically is that group members need focused opportunities to exchange ideas and make decisions about group mission, values and vision. Doing an exercise like this can encourage people to develop their visions, loosening imaginative powers rather than falling into a polarized argument.