Denkstahl is a young art project, part of which takes place in the urban space. The artist is out and about with stickers and chalk, he resorts to the public spaces and the streets to leave a mark. Art the surrenders to its surroundings, the proverbs, asking for sense and reason, images and words, that disappear again after a few days: The artist accomplishes all of this by using the natural material of chalk and coal. They are CFC free, environmentally friendly and therefore biologically, organically degradable. Comparable to the sand paintings of the Tibetans and the Navajo Indians, this form of expressing art is perishable and can dissolved by rain (it can also simply be removed with water). It exists only for a certain time permitted by the natural flow of life. This kind of transience emphasizes the dynamism of emergence and passage within the cycle of life and is essentially part of its art. As in the art form of Zen Buddhism, it symbolizes the process of letting go.