This conclusion presents some closing thoughts on concepts discussed in this book. A fundamental assumption of adult cognitive neuropsychology is that there is modularity in the organisation of cognitive systems, in that there are discrete and relatively independent subcomponents within cognitive systems that function in a semi-autonomous way. In surface dyslexia, there are high levels of regularisation or valid errors and low levels of morphological errors. In phonological dyslexia, there are high levels of morphological errors but low levels of regularisation or valid errors. The double dissociations between surface and phonological dyslexia and their straightforward interpretation in relation to multiple route models of reading argue strongly for the mutual independence of the phonological and semantic reading route during development. Within the spatial and perceptual disorders, there appear to be double dissociations in relation to the putative three channels of visual perception dedicated to form, movement, and position.