“Whatever is joined to an article is counted as the article itself.”
The handle of an ax, the parts of a stove, a bundle of clothes stitched together – even a group of keys on a ring. They are treated as one object and can be dealt with as such on the Sabbath.
I'm interested in the way we think about objects: how we move from a collection of individual parts into a new "whole" which we treat differently. Don't we do the same with groups of people (political parties? religious communities?)