This was the reason for going to Philadelphia — to visit the Barnes Collection, particularly before it closes and moves to its new facility, across the river and down the road as you enter the city on the Philadelphia Parkway. You won’t be able to miss it and millions of people are expected to attend. At least, the Philadelphia Museum of Art is banking on it. It is the most extensive, impressive and diverse private art collection in the world, worth billions and probably priceless. Our visit was prompted by the documentary that Peter and I watched over a year ago called, The Art of The Steal, a film by…