LONDON — “I buy, I buy, and can’t stop myself,” said Edward Degas, famed French impressionist painter. “The trouble is that people are beginning to know about it and are bidding against me. They know that when I want something, I absolutely must have it.”  As much as Degas is known for his own work, his art collection was weighty enough to merit a three day Paris sale in 1917 that spanned master artists like Monet, Bartholomé and Pissarro among many others. In total, his collection featured 500 paintings and 5,000 prints. Watch Anne Robbins, curator of “Painters’ Paintings: From Freud to Van Dyck” at The National Gallery in London, as she walks through Degas’ collecting habits and how his collection influenced his work. The exhibition is on through September 4 and also includes works that were in the collections of Freud, Matisse, Leighton, Watts, Lawrence, Reynolds, and Van Dyck. For more information, www.nationalgallery.org.uk.