With Taya Thurman, 1970. Photo: Horst P. Horst/Conde Nast/Getty Images For nearly 30 years, the arts patron Christophe de Menil had the same event on her Hamptons calendar: the Watermill Center’s annual summer benefit. The center’s founder, Robert Wilson, was one of her closest friends, and she had effectively underwritten his career after seeing his experimental play A Letter for Queen Victoria on Broadway in 1975, sending him a check for $25,000 with a note that read, “Thank you for this