Gilbert’s premise is to explain how the human mind works, particularly when it comes to perception and memory, and relate those concepts to our perceptions of how happy we are. He starts out with some fun scenarios like how siamese twins do not choose to be separated because they are happy being together, but no one would choose to become physically attached to someone else, and asks, “why?” He explains scientific studies that have been used to illustrate the concepts he discusses, which gives validity to his suppositions. The studies and examples start to feel repetitive about midway through, probably because the idea isn’t very complex. If you like books in this vein you will probably recognize many of the studies (how happy you remember something making you versus how happy it actually made you, etc), so there probably isn’t much new here for you. If you’re interested in psychology, it’s a good, easy to understand introduction to perception, but knowing how the mind works doesn’t necessarily mean you can do anything about it.