brookter wrote:...how far does the concept of a motion verb extend.
I think you may be thinking about this in A&G: Hoc apud A&G tractas, nisi fallor:
A&G, §509 wrote:NOTE 2.—The supine in -um is occasionally used when motion is merely implied.
The way to think of it, I suspect, is to believe that a supine can be used with a motion verb (venire, ire etc) for situations where motion is less obvious; for example, "amatum [the supine] iri" is like "amaturos esse" = "that they are going to love" (no actual motion).Meliùs est ità comprendere, ut suspicor: licet supino uti cum verbo motûs (ut venire, ut ire), etsi motûs non manifesti. Exempli gratiâ, "amatum [supinum] iri", quod synonymum "amaturos esse" verbi est et motûs inops.
I'm writing in Latin hoping for correction, and not because I'm confident in how I express myself. Latinè scribo ut ab omnibus corrigar, non quod confidenter me exprimam.