 Finally, the notion of naturalness and the related notion of sparseness, familiar especially from Lewis’s work (see Lewis 1986, 2009; Schaffer 2004; Dorr &amp; Hawthorne 2013; McDaniel 2013, 2017; Thompson 2016a) is sometimes connected with fundamentality. Sider’s (2011) influential notion of structure is closely related to the notion of naturalness. Perfectly natural properties might seem to be good candidates for absolutely fundamental entities. Naturalness is no doubt a close cousin of fundamentality, but there are some reasons to think that the two notions cannot do the same jobs (see Bennett 2017: Ch. 5.7). Most strikingly, there may be perfectly natural entities that are dependent in ways that are clearly ruled out by many of the definitions of fundamentality that we will shortly  consider.[4]  For further discussion, see the supplement on  the natural/non-natural distinction  in the entry on  David Lewis’s metaphysics.