Read this today and loved it:
We have an idea that art is self-expression--which historically is weird. An artist used to be seen as a medium through which something else operated. He was a servant of the God. Maybe a mask-maker would have fasted and prayed for a week before he had a vision of the Mask he was to carve, because no one wanted to see his Mask, they wanted to see the God's. When Eskimos believed that each piece of bone only had one shape in it, then the artist didn't have to 'think up' an idea. He had to wait until he knew what was in there -- and this is crucial. When he'd finished carving, his friends couldn't say 'I'm a bit worried about that Nanook at the third igloo', but only, 'He made a mess getting that out!' or 'There are some very odd bits of bone about these days.'
Impro Improvisation and the Theatre. Keith Johnstone. 1981, pg 79.
Thanks for the excellent recommendation, Matt.