Tucker explains that the first two lines are a "manifest allusion to the words of the Marriage Service: 'If any of you know cause or just impediment why these two persons should not be joined together in holy matrimony;' cf. Much Ado 4.1.12. 'If either of you know any inward impediment why you should not be conjoined.' Where minds are true - in possessing love in the real sense dwelt upon in the following lines - there can be no 'impediments' through change of circumstances, outward appearance, or temporary lapses in conduct." (T. G. Tucker, ed. Sonnets of Shakespeare. Cambridge: University Press, 1924, )
Written for medium high voice, this setting is colored with pleasant diatonically related polytonal colors, as the vocal line rises and falls with the sense of the various quatrains and couplet of this well beloved text. The last lines are remarkable for their argument, which disallows and disavows its own possible opposition. For that the concluding couplet is set as an afterthought, in a quasi recitativo style before the final cadence.
The score is available as a free PDF download, though any major commercial performance or recording of the work is prohibited without prior arrangement with the composer. Click on the graphic below for this piano-vocal score.