 Sharing of [the perfectly natural properties] makes for qualitative similarity, they carve at the joints, they are intrinsic, they are highly specific, the set of their instances are ipso facto not entirely miscellaneous, there are only just enough of them to characterise things completely and without redundancy. Physics has its short list of ‘fundamental physical properties’: the charges and masses of particles, also their is so-called ‘spins’ and ‘colours’ and ‘flavours’, and maybe a few more that have yet to be discovered. (Lewis 1986b, p. 60, author’s emphasis)]