Tim's Vermeer - Go See It

How does a painting come to be?

Last weekend in Toronto we went to see "Tim's Vermeer"...the story of Tim Jenison's quest to figure out how what could be the best painter - ever - did it.   What made his paintings stand out and stand the test of time (as in several centuries)?

The answer to 'how' is that he most likely had help in the form of mechanical aids - a simple lens and a simple mirror.   This combination allows the painter to ensure that the color he paints matches the color of the setting.   Now, there is no letter from one of his contemporaries like Pieter de Hooch saying,

"Dear Johannes...can I borrow your studio and lens/mirror contraption for the next 18 months to paint, can't seem to get the light quite right here across the river."

But as the scholars in the movie discuss, the painting itself gives clues on how it might have been done.  The light raking across the wall, the curve in the seahorse's tails most likely wouldn't have been painted the way they were - without help.  Using tools of the era, including grinding/polishing his own lens, Jenison takes us thru the five years it took to go from concept to final painting. 

The painting in question is "The Music Lesson" hanging in Buckingham Palace.

Is this the original, or the one created by a man who didn't paint?