> The problem is that there isn’t a tidy image (at least I haven’t come up with one) that combines all of it.
I don't think you should expect there to be an image that shows all the levels of abstraction at once. The image should only show you the level of abstraction that you're currently concerned with: in this case, endofunctors and the natural transformations between them.
What you're asking for is akin to asking for an architecture diagram of a distributed system that somehow also shows you the circuits inside the CPUs.
The point of abstraction is to package up details into a box and forget about them, for the purpose of managing the complexity as you reason at a higher level.
I don't think you should expect there to be an image that shows all the levels of abstraction at once. The image should only show you the level of abstraction that you're currently concerned with: in this case, endofunctors and the natural transformations between them.
What you're asking for is akin to asking for an architecture diagram of a distributed system that somehow also shows you the circuits inside the CPUs.
The point of abstraction is to package up details into a box and forget about them, for the purpose of managing the complexity as you reason at a higher level.