Pound wrote that one shouldn't trust opinions about writing which had been
offered by someone who hadn't himself written anything of note.  He said it
would be better to read Henry James's prefaces than any number of books
about novels by non-novelists. As advice goes, that seems reasonable to me,
though, as always, there are exceptions.

There was a documentary on TV several years ago about the huge building
stones of Machu Picchu which,  although no mortar was used to join them,
fit together so perfectly that you cannot pass a knife blade between them.
They're irregular in size and shape. Some have more than two-dozen
corners.  An American academic had theorized (in the late 20th century)
that such wondrous workmanship was the result of advanced science among the
Incas. He claimed they were technologically so advanced that they would
have been able to fabricate huge polished dishes made of gold -- about as
big as those large satellite dishes that folks living in the boondocks put
in their yards to get TV --  and the dishes could focus a beam of sunlight
onto the stone and thereby cut it into the desired shape.  A stonemason on
site mumbled something about the academic being a $&$#^ idiot; the focused
beam was barely strong enough to cut through a popsicle stick. He reached
down and picked up a small rock from the ground.  There were many such
rocks strewn all over the ground.The rock was about the size of his shoe.
He said, Just look at the strike marks on the big stones; they used rocks
like the one I'm holding in my hand to shape them.

Tim Romano