In 1821, the German physicist Thomas Johann Seebeck discovered the thermoelectric effect in Berlin, observing that a voltage was produced when two different metals were joined and heated at one junction. This unexpected generation of electricity from heat alone, without any battery or magnet, revealed a previously unknown connection between thermal and electrical phenomena. Seebeck's discovery in Berlin opened the field of thermoelectricity and led to the development of the thermocouple, a device still used today for temperature measurement in scientific and industrial applications.

Seebeck's discovery that heat could produce electricity suggested that all forms of energy were interconnected in ways not yet understood, a theme that resonated with German Romantic literature's fascination with hidden correspondences and the unity of all natural forces. The thermocouple's ability to translate heat, the most primal and dangerous form of energy, into the controlled language of electrical current provided a metaphor for the civilizing power of art that appears in the works of Goethe, who knew Seebeck and shared his interest in the interconnections of natural phenomena.