 Essentialism. Phenomenological ontology is committed to a form of essentialism according to which objects are constituted by an essence. It should be noted that the word “essence” (Wesen) is ambiguous (Reinach 1912): on the one hand, it can refer to the so-being of an individual object, i.e., to that which makes an individual the individual it is. For instance, how finely a given quill pen writes is a property that qualifies this individual pen as the pen it is—for no other pen can write in the same fine way (Héring 1921: 496f; Héring reserves the term, “essence” (Wesen), for this concept; see also De Santis 2015, Fabbianelli 2016). On the other, it can also indicate the what-being of a given object or the kind to which it belongs: e.g., being a pen is one such kind (Héring uses the word “essentiality” (Wesenheit) to refer to essence in this second sense, see 1921: 505ff and Seifert 1996). Essences (in this second sense) ground necessity (Héring 1921; Ingarden 1925; Reinach 1911b). For instance, the essence of promise, color, movement, or tone grounds the necessary facts that promises generate claims and obligations, that colors have extension, that movements have velocity, that tones have pitch and intensity, etc. (see also Mulligan 2004; Fine 1994a,b, 1995). Essences are taken to exist independently of whether they have exemplifications or not. As such, they are described as ideal (abstract) and atemporal objects. Not all essences are atemporal, though: for instance, Geiger discusses the idea of “dynamic essences” (Geiger 1924, e.g., the essence of the tragic), which evolve through time and are characteristically instantiated in artworks.