AbstractThe machine theatre in France achieves its peak in the second half of the seventeenth century. It is the construction of machines that permits the adequate representation of the third dimension on stage. This optical illusion is created by flying characters, as heroes, gods, or demons moving horizontally and vertically. The enumeration indicates that only characters possessing either ethically exemplary character traits or incorporating sin are allowed to fly. Therefore, the third dimension indicates bienséance – or its opposite. According to this, the following thesis is deduced: The machine theatre illustrates via aesthetic concerns characterising its third dimension an ethic foundation. Ethic and aesthetics determine each other in the context of both, decorum and in theatre practice. In order to prove this thesis three steps are taken. First of all, the machine theatre’s relationship to imitation and creation is explored. Second, the stage design, representing the aesthetic benefits of the machines in service of the third dimension, are explained. Finally, the concrete example of Pierre Corneille’s Andromède is analysed by pointing out the role of Pegasus and Perseus.