  That said, combinatorialism can arguably provide a reasonably robust  analysis of intuitions about the essential properties of ordinary  thick particulars like dogs or persons. Such objects can be taken to  be temporal successions of sums of simples and each sum in the  succession as its temporal parts. Sums in the same rough temporal neighborhood are composed of roughly the same simples and are  structured in roughly the same way. Similarities between such objects across worlds in turn determine counterpart relations. Following  Lewis, the essential properties of such objects can then be  identified with those properties exemplified by (all of the temporal  parts of) all of its counterparts in every world in which it exists  (Armstrong 1997, 99–103,   169).[57] 