Tim,
Which Da Vinci's exactly? Can you post the pictures with your comments? It's hard to understand how you came to such a conclusion.
When you say, 'when did painting mature' then do you believe that it is still in the mature state?
I personally think 'The Syndics' by Rembrandt is as mature as the art of painting can possibly get. Bouguereau does not even come close... in my humble opinion.
http://www.rijksmuseum.nl/asp/showim...Z/SK-C-6.Z.jpg
Peter
After giving it some thought I wanted to edit this post and add that I think I agree with Tom. Van Eyck wasn't a less mature painter than Rembrandt. I personally just don't understand the very high regard some people have for Bouguereau. Maybe an idea for another thread?