Shakespeare's Sonnets: How can my muse want subject to invent

How can my muse want subject to inventWhile thou dost breathe that pour'st into my verseThine own sweet argument, too excellentFor every vulgar paper to rehearse?Oh give thy self the thanks if aught in meWorthy perusal stand against thy sight,For who's so dumb that cannot write to theeWhen thou thy self dost give invention light?Be thou the tenth muse, ten times more in worthThan those old nine which rhymers invocate,And he that calls on thee, let him bring forthEternal numbers to out-live long date. If my slight muse do please these curious days, The pain be mine, but thine shall be the praise.