>Monads have no extension in physical space or physical time.
>
>They are not physical objects made of physical matter in physical space or time.
>
>We could imagine them existing in some type of space and time, just not the physical space and time we know and love.

Distance functions can be defined over all sorts of "sets". The definition of the distance is not always related with the common distance definition for Euclidian space.

To give yet another example, when sending data over the Internet, data is sent over several links. It is the task of a routing protocol to find the best route from one place to another. A "distance function" or "cost function" is used here; it might consider the number of hops (through how many routers must the information pass), or a high cost (distance) may be assigned to a low-speed connection. The equipment exists in physical space, and a "physical distance" exists, but it is quite irrelevant for the routing protocol.

>Sure, you could. If the monads had windows. But they don't.

What do you mean with "have windows"?

>Consider their properties PRIVATE.
>
>You cannot determine their x (y or z).
>
>Now how far apart are they?

That would depend on how you choose to define "distance".