In this installation by Jürgen Knubben past and present collide: the lentil or lens-shaped steel constructions lie next to stones of similar shape and size. The stones (slate) are what is known as geodes – around 180 million years old! The steel lenses, on the other hand, were created around 1980. Another object was added to the flat shapes – a »leaning tower« that resembles an obelisk. Obelisks were erected in Egypt around 2000 B.C. as cultic stones to honour the sun god. So it is possible to see in the »leaning tower« a connecting link between the distant past of the earth’s history, represented by the geodes, and modernity.