 Thomas Aquinas adopts Avicenna’s distinction already in his early On Being and Essence (De ente et essentia IV). Essence can be considered either in itself or with respect to its existence in the soul or in the particular things. Universality and particularity are accidents of essence, which in itself is neither universal nor particular. Thomas Aquins adopts the expression “accidents of essence” from Averroes (Comm. magnum Metaph. IV.3). The universal, according to Thomas, is a natura communis, which has existence only in the intellect. Individuals are essences individuated by matter with quantitative dimensions, but only at the time of their origin; later individuation is due to the form. In later writings, Thomas develops his concept of essence and existence so that existence is that which actualizes essence (Summa theol. Ia q. 3 a. 4) (Wippel 1990; Black 1999).