A flowerpot, a petri dish or a bioreactor are all small types of a hortus conclusus, the enclosed paradisiac green garden. Medieval representations of the hortus conclususoften contain a unicorn that stands in as a symbol for the maiden and pure nature. The “new unicorns” growing in laboratories are not only immaterial imaginations. They constitute the real matter of incarnated ideas. “Unicorns” are still fabulous objects but they awake to life. But a “unicorn” isn’t a mere metaphor or allegory in art any longer. And art isn’t any longer a semiotic system only. Art becomes a metabolic system. This is the crucial point: It has the capacity to make fine art contemporary and specific. Metabolisms enable art to enter reality; they connect artworks with processes in nature and society, and our daily life. An artwork is a clash of the symbolic realm and the realm of the real. Only the transformations and translations between those spheres bring an artwork into the world. Therefore, green has to be considered as a “metabol,” not just as a color. It involves metabolic processes and becomes a universal topic ranging from thermodynamics to global economics and the processes in our brain. In art history, green was a symbol, now it becomes a “metabol”.