This conclusion presents some closing thoughts on the concepts discussed in the various chapters of this book. This chapter outlines what seem to be the most interesting and important issues to emerge from research into human intelligence. There are very few other areas of psychology where seemingly dissimilar variables correlate so substantially. Where variables do correlate substantially in psychology, there is frequently a nagging concern that the two variables share things in common pretty much guaranteeing that two variables will be correlated. For these reasons, the author believe that research into the nature and origins of human cognitive abilities are interesting, important for psychology, and also of considerable practical use. The chapter discusses the "Flynn Effect" that is applied to tests of g and fluid ability, and not to crystallised ability. Neuroscientists study the plasticity of the neural system following damage and are at pains to stress the flexibility and resilience of the human nervous system.