Constellations started as a therapeutic process done in a group setting, or Circle.  One occasion I host a Special Event Workshop on a specific theme.  During a Circle or Workshop, another person, best a stranger in fact, represents someone that is part of the issue you are trying to resolve or is an element of yourself in the case of a "self constellation."   The parts interact naturally showing the story between them and therefore illustrating the reality of the situation.  A Circle setting gives form to the topic being constellated and makes it easier to interpret because of the images that emerge.  A common question comes up: How is it that the people react as they do?  Your "field" or personal "system" is the answer.  For science lovers, this has basis in quantum mechanics and is explained by a morphic field.