 A preliminary caveat is in order. It concerns the very notion of ‘part’ that mereology is about, which does not have an exact counterpart in ordinary language. Broadly speaking, in English we can use ‘part’ to indicate any portion of a given entity. The portion may itself be attached to the remainder, as in (1), or detached, as in (2); it may be cognitively or functionally salient, as in (1)–(2), or arbitrarily demarcated, as in (3); self-connected, as in (1)–(3), or disconnected, as in (4); homogeneous or otherwise well-matched, as in (1)–(4), or gerrymandered, as in (5); material, as in (1)–(5), or immaterial, as in (6); extended, as in (1)–(6), or unextended, as in (7); spatial, as in (1)–(7), or temporal, as in (8); and so on.