What a delightful puzzle, in the main part -- I thoroughly enjoyed the jigsaw pieces, and found that a very creative and novel touch.
As others have noted, the endgame seems a bit weak. I don't mind an extra chunk of puzzling in the endgame, but didn't get on well with this one. Like others, I initially struggled to see how a block of symmetric cells could be said to "start and end" at the starred cells -- thank you dodgepot@35 for elucidating that. With that condition to box it in, and the letters that are not in the quotation, the solution could indeed be described as unambiguous, but hardly, I think, as beautiful, obvious, or straightforward. In fact, at the moment it seems to me ugly, obscure, and difficult! Like others here, beyond the crude general shape I can't see the significance of it. An emoji? A reference to the films? Not sure. Looking back at all the posts in this thread, as drxx has pointed out, this one does not quite seem to have the value or power the quotation claims for its kind!
And I cry foul for the quotation. The author given did not write the quotation in the form we are expected to find (33 letters). He wrote another form, with a different fifth word, and then a few years later he wrote another form which omits the third word. And the well known form of the quotation actually appears in print several years before either of his versions. There's a Wikipedia article (titled, of course, as per the well known form of the quotation) whose 'History' section sets it all out in neat and verifiable detail.
So I've just had a nice cup of tea to wash away the taste of the endgame. Many thanks to everyone here who posted trying to help, delicately, to clarify it. Well done everyone who has got there. I'm going to remember the jigsaw pieces fondly and now put the rest out of my mind. Many thanks, Xanthippe, for a delightful and original grid fill.