A group of Kinetic artists formed in Düsseldorf in 1957 by Heinz Mack and Otto Piene, who were joined in 1961 by Günter Uecker (there were other members from time to time, but these three formed the core). Their views were put forward in a periodical, also called Zero (two numbers appeared in 1958 and a third in 1961). Although they were interested in technology, they stressed the importance of working with nature, rather than against it, and carried out several environmental projects. They also—unlike many Kinetic artists—valued the intrusion of the irrational in their work. The group disbanded in 1966.