I found a new blog -- well, new to me anyway -- David Apatoff's "Illustration Art" -- and since the author is a notorious "Grumpy old man", I'm sure to be visiting it often.
This post caught my attention first -- since I agree -- in the world of famous European drawings -- Michelangelo's Sybil is the most incredible -- and I probably wasn't the first art student to try to copy it -- and fail.
But I remember an exhibit of drawings that passed through Chicago about 12 years ago - and it had a 17th C. copy of the "Ignudo" --- another great study for the Sistine Chapel -- and I've never forgotten how good it was -- but how it was still unmistakably different from the original.
Can you see how the copy is different ? -- in the way that one performance of a Beethoven sonata HAS to be different from another -- as long as the copyist is re-imagining the forms -- and filling them with his own spirit (and not just doing a point-to-point mechanical copy)