In 1732, the French chemist Charles Francois de Cisternay du Fay announced his discovery of two distinct types of electricity at the French Academy of Sciences in Paris. He observed that some charged objects repelled each other while others attracted, leading him to propose the existence of "vitreous" electricity (produced by rubbing glass) and "resinous" electricity (produced by rubbing amber or resin). This binary understanding of electrical charge was a major conceptual advance preceding modern positive and negative terminology.

Du Fay's discovery of two opposing electrical forces provided a scientific framework for the literary theme of duality that pervades eighteenth-century and Romantic literature. The idea that a single fundamental force could manifest in two opposing forms resonated with poets exploring themes of attraction and repulsion in love, the dual nature of the soul, and the tension between reason and passion. French Enlightenment writers like Diderot drew on such scientific dualities in their philosophical and literary works.