I think I'm the only one I know who loves this book--so I have to stick up for it. OK, I would have given it 4 1/2 stars, if that had been an option, because I don't think Tepper has ever quite come back up to the standard she set in "Grass," "Raising the Stones," "After a Long Silence," and "Gate to Women's Country" (although "Fresco" comes close, and "Gate" has had trouble holding up over time).
The theme of "Shadows End" is invisibility. What (and whom) do we see and not see in our worlds? What stops us from recognizing what's there? Tepper returns to this question in a myriad of ways, both directly and obliquely (visibly and in shadows). It spoke to me deeply. And in such remarkably lovely, deft prose!
The end of the book (stop here if you don't want a real hint) breaks all the rules of writing--it's exactly what your English teachers told you never to do. It's absurd and a little unbelievable, but it also left me in awe at the author's deliberate violation of all conventions. Wow!