Given that there is now a theory of intelligence, there should also be a scientific theory of stupidity. In fact, teaching this theory as a central part of all courses at all educational levels would produce enormous benefits for our society. The first of these would be a vaccine against stupidity, an urgently needed prophylaxis‰. The first line of José Antonio Marina‚s new book makes an attempt to answer questions that we all ask ourselves: Why do we always make the same mistakes? Why do we spend so much time spoiling our lives? And, why do intelligent people often behave so stupidly?