Janus has become the symbol for ambiguity, duality. Nowhere is this more exemplified than in advances in science and technology. From the beginning of humanity, these advances have brought higher survival rates, better health and quality of living. At the same time, they have been turned against humans and the environment. Fire, iron, horses, and – in modern times - reactive chemicals such as chlorine, mass production, vehicles, airplanes, submarines, nuclear energy, „omics“ and IT serve to illustrate this point.