I love reading scientific books which are wrote for normal people. Even if it's kinda old like this one, that have been published in 70's. This outdatedness make it more understandable for common reader, and make them want to read most recent published works. Oliver Sacks have a jungian view about spiritually but he tries to stay scientific and never say sth of the sort with certainty but with wonder about possibilities that cross his mind. And it is the secret of his readability. Which make his work nearer to literature than most scientific writings.