Work is not only a concept of physics, for much longer and more importantly it has been an existential humane category. Throughout history man has used his brain to make work easier and more effective, to make life better and more satisfying. He has been developing and applying new tools as well as new ways of human cooperation and social organization complementary to these new tools. Man's role in man-machine systems must be seen in this context. The paper analyses the changes the man-machine relationship has undergone; it shows the negative consequences of 'Taylorism', the adverse effects to both man and machine caused by specialization of work and segmentation of life. The advent of automation, information technology, micro-electronics offers the chance to reverse this development, to open up new options and real human choice. Technological needs and human aspirations meet in the search for new patterns of work organization and for new relationships between man and machine, offering man the role as knowledgeable, educated and motivated master of the machine. This is illustrated by several practical examples, proving that technology is not deterministic. There are always feasible alternatives available which will result in considerable improvements and even in the creation of new work places if decisions are taken not for but with the people concerned. The application of participative methods in designing man-machine systems, the development of alternatives which consider the needs of man and society has become the main challenge to scientists and engineers of our time. Meeting this challenge will not only reconcile and reunite designers and users, it will in the long run spell the return from the belief in machines to the belief in the humanities, the return of the power of decision-making from a few privileged to a computer-assisted democratic system.