What does this quote mean “...was everyone else really as alive as she was? For example, did her sister really matter to herself, was she as valuable to herself as Briony was? Was being Cecilia just as vivid an affair as being Briony? Did her sister also have a real self concealed behind a breaking wave, and did she spend time thinking about it…if the answer was yes, then the world, the social world, was unbearably complicated…but if the answer was no, then Briony was surrounded by machines, intelligent and pleasant enough on the outside, but lacking the bright and private inside feeling she had.” from the story The Atonement by Ian Mcewan?