Dreams are often strange, unexpected yet somewhat familiar. One gets to interact with the world but in many cases the response is unexpected. In a virtual environment objects have to initiate such interaction in order to loosen the viewer from his often passiv position - making him a participant rather than a viewer.
A strong motiv for such interactions are symbpols. Here the vessels can be percieved as if they would hold other objects or even memories and ideas. Something should happen, once the viewer decides to interact with the vessels. In this particular world s/he gets transmitted to anoter world - another state of exploration.