The packaging hypothesis
Let’s suppose you have a box. Ideally this is no mere supposition but you actually have a box nearby right now. If you don’t, you’ve surely had one at some point, so in that case we’ll talk about that box.
Boxes are made for storing things. You can put all sorts of things inside your box. You could even put another box inside it.
And you needn’t stop there. Another box can go inside your boxed box, or you could even put multiple boxes alongside each other inside the original box. All manner of boxes …