On Monday, Sept. 15, mere hours after Lehman Brothers declared bankruptcy in New York City, Sotheby’s was throwing open the doors of its London headquarters for the most extravagant sale in the auction house’s history. The sale, of 223 new artworks by Damien Hirst, brought in more than $200 million — nearly 10 times the total receipts of the previous record-holder for a single artist, a 1993 auction of 88 Picassos that reaped around $20 million. It was a level of consumption that, particularly when viewed against the concurrent collapse of the financial-services industry, almost immediately acquired a nostalgic air, the last gasp of the art boom.