What is the theme in How Proust Can Change Your Life ; Not a Novel by Alain de Botton?

The value of suffering is the main theme. Author De Botton points out that Proust, despite all the advice he dispensed for better living, suffered psychologically and emotionally for much of his life. Psychologically, he had low self-esteem, was a closeted homosexual, reclusive, and had many fears. Physically, Proust had near-constant colds and allergies and was often confined to bed.