Salinguerra is the foil of the political, as Eglamor of the literary, Sordello, and the dramatic interest of the whole poem focusses in those two scenes.

He had enough of the lonely inspiration of genius to vanquish the craftsman, but too little of its large humanity to cope with the astute man of the world.

When Salinguerra, naturally declining his naive entreaty that he should put his Ghibelline sword at the service of the Guelph, offers Sordello, on his part, the command of the imperial forces in Italy if he will remain true to the Ghibelline cause, he makes this finite world more alluring than it had ever been before to the "infinite" Sordello.

After a long struggle, he renounces the offer, and--dies, exhausted with the strain of choice.
[Footnote 15: There are other Shelleyan traits in _Sordello_--e.g., the young witch image (as in _Pauline_) at the opening of the second book.] What was Browning's judgment upon Sordello?
Does he regard him as an idealist of aims too lofty for success in this world, and whose "failure" implied his triumph in another, where his "broken arc" would become the "perfect round"?
Assuredly not.

That might indeed be his destiny, but Browning makes it perfectly clear that he failed, not because his ideal was incommensurate with the conditions in which he lived, but because he lacked the supreme gift by which the greatest of souls may find their function and create their sphere in the least promising _milieu_,--a controlling and guiding passion of love.