Joel Spolsky points to this brillant article by Clay Shirky. One of its topics is that you can analyze a group by looking at it as a whole, or at the invidual members, but never both at once. Very true!

It seems to me you could make an analogy to music - you can listen to a piece of music as a whole, or you can follow one of the voices or instruments, but never both at the same time. Why is this important? It’s not, but it struck me as a nice metaphor ;-)