essence

The Latin 'essentia' did not grow organically from Roman speech. Cicero invented it around 45 BCE in his Academica to render the Greek philosophical term 'ousia' (οὐσία), which Aristotle used in the Metaphysics to mean the fundamental being of a thing. 'Essentia' derives from 'esse' (to be), itself from the Proto-Indo-European root h₁es- (to be), making it a philosophical coinage built from the oldest grammatical material in the language.

Greek 'ousia' had a broader life than what Cicero captured. In Plato's dialogues of the 4th century BCE, 'ousia' could mean property or wealth as well as philosophical being. Aristotle narrowed it in his Categories (c. 350 BCE) to mean the primary substance of a thing: what it actually is when stripped of its accidental properties and qualities. Cicero's 'essentia' inherited that narrowed Aristotelian sense and carried it into Latin.

Medieval scholastic philosophers writing between the 11th and 15th centuries made 'essentia' central to their debates. Thomas Aquinas (1225-1274) distinguished 'essentia' from 'existentia' in his De Ente et Essentia (1252): essence is what a thing is; existence is that it is. This distinction shaped Western philosophy for centuries. The word 'essence' carried that precision into English when it was borrowed from Old French around 1380.

Within a century of its entry into English, 'essence' had split into two registers. Apothecaries and perfumers used it for the concentrated extract of a plant or substance. Philosophers continued to use it in the Aristotelian sense. By the 17th century both uses were well established, and the word that Cicero built as a translation tool had become native to an entirely different language, doing double duty in the laboratory and the lecture hall.