 Like anyone in pre-set theoretical times, Twardowski has a very broad notion of (proper) part, covering much more than just the pieces of an object. Twardowski distinguishes material and formal parts of an object. The material parts of an object comprise not only the pieces of an object, but also anything that can be said to be a component of it, such as the series 1, 3, 5 is composed of three numbers (namely, 1, 3, and 5). Among the material parts of an object are also its qualities (Beschaffenheiten) such as extension, weight, color, etc. (1894, §10, 58). The formal parts of an object are the relations (Beziehungen) obtaining between the object and its material parts (primary formal parts) as well as the relations obtaining among the material parts themselves (secondary formal parts) (1894, §9, 48 and ff.; §10, 51 and ff.). 