 Among the most influential philosophical doctrines of Arabic origin is the distinction between essence (māhiyya, essentia) and existence (wujūd, ens), which the Latin West got to know from Avicenna’s Metaphysics, chapters I.5 and V.1–2. The distinction was very influential historically: it found adherents among philosophers and theologians of the Arabic, Hebrew and Latin cultures. The essence-existence distinction was used by Avicenna in several metaphysical contexts, i.e., in the discussion of primary concepts, of universals and of the first cause. The following presentation focuses on the context of universals. Avicenna’s core idea was to differentiate between two components of universals: essence and universality. The essence of “horseness”, to use Avicenna’s example (Metaphysics V.1), is in itself neither universal nor particular. Only existence, which in itself is distinct from essence, adds universality or particularity, depending upon whether “horseness” exists in the mind, that is, as a universal, or in the exernal world, that is, as a particular. In some of his writings, Avicenna emphasizes that there is universality only if the essence is found in several objects in the external world (Marmura 1979, 49).