Sorry..the "ask the Greeks" applied to the Golden Mean mentioned perviously, essentially proportions found appealing to the eye in general.       The rules are not hard rules but "rules of thumb", suggestions which usually work quite well in aligning components of a composition.  Still, the content of the compo must rule in the end...quite likey you will find that most pleasing crop,etc. then notice it does somehow fit those rules...simply pleasing to the eye.  Then again, masters as mentioned previously have broken the "rules" and done so by their masterly work.   Content has much to do with the use of rules, it appears to me.

Macros are a point of that.  Typical macros often throw all rules out the window in favor of the close detail of the shot to make it work and amaze.  Then again, a few macros which are better balanced...are indeed more than just another macro and something more beautiful to behold.

Sure, I bend and break the rules all the time..still, much of what looks best in 
final render does fit the rules to some extent.   Look at some of your best shots and see.       Tom.