Magnetic lines of force

In another thread, George Dishman explained:

I think you understand my point of view here, that 'x' and 'y'
are conceptual while the paper that holds the dots apart is real.

Could you apply this same kind of wonderfully clear exegesis to
the term "magnetic lines of force"? I keep seeing intimations
that they have some kind of reality. Thank you!

-- Jeff, in Minneapolis

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