[claudiawerner]

Being "made up" (what I think GP means by "imaginary") doesn't mean that such things lack force. For instance, class is "made up" and some ontologies of race and gender fix them as "made up" - this does not, of course, mean that class, race and gender do not have very real effects on society and the individuals therein. But humans have power over human abstractions, so such "made up" things can be changed, as opposed to what I presume OP would group into things not "made up", such as the laws of physics. Being "made up" hints to a possibility, no matter how remote, of a different (and dare I say better) world.

[EpicEng]

Calling them "imaginary lines" was an obvious attempt by the GP to disregard them as meaningless. They are not meaningless, that was my point.

[claudiawerner]

But by the same token, if we assume that GP is more than a simpleton (in the principle of charity) we must say that they would also consider art (always created by human intention) to be "imaginary lines", but I doubt they would deny paintings can have meaning. Words (usually though not always naturally evolved), by the same token, are just scrawls, but they have meaning despite being "made up" in the same way. GP knows they have meaning because he/she is using them in such a way. I read the idea that the lines are imaginary to mean that they don't have to be that way.