Esse

Esse is the Latin infinitive meaning “to be” and the root of the verb sum. In Latin grammar, esse represents existence rather than a specific attribute. The principal parts most commonly cited for sum are sum, esse, fui, futurus; the present indicative forms are sum, es, est, sumus, estis, sunt. The infinitive esse is used to express being in general and appears in various verbal constructions throughout Classical and Medieval Latin.

In philosophy, esse has a distinct technical role. A long-standing distinction in Aristotelian and later Scholastic thought separates essentia (essence) from esse (existence). Esse denotes the act by which something exists, often called the act of being (actus essendi). This distinction underpins debates about what it means for something to be and why there is anything at all. In Thomas Aquinas and other medieval writers, God is described with phrases such as ipsam esse subsistens to indicate a necessary, self-subsisting existence different from created beings.

Outside technical discussions, esse appears in the history of ontology and the history of philosophy as a term for existence itself. In modern usage, the Latin term is mainly studied within classical philology, history of philosophy, and related fields. The word has influenced the English vocabulary through derived forms such as essence, essential, and existential, all tracing back to the root of being expressed by esse. In Romance languages, descendants of esse (for example, Italian essere and French être) continue to serve as the basic verb for “to exist” or “to be,” reflecting the term’s enduring legacy in the study of existence.