India, June 7 -- In 2nd-century Rome, even toilets weren't private. Royalty and nobility sat side by side, on elaborately decorated commodes arranged in rows, to chat through their ablutions. Solitude was sinister, the 16th-century German priest Martin Luther warned. "For the devil watches and lies in wait for you most of all when you are alone." Privacy of thought, place, emotion is not a human instinct. In fact, it could be said to be quite unnatural, albeit unquestionably vital, says British writer and cultural historian Tiffany Jenkins. In her book, Strangers and Intimates: The Rise and Fall of Private Life, Jenkins traces this arc over centuries, to the status of coveted asset; a means for intimacy, self-discovery, freedom. It is a fra...