In addition to a general presentation of the facts, the author has expanded into areas of current debate The aim of this book is to provide a general guide and it is not intended as a substitute for a consultation with an appropriate specialist in respect of individual care and treatment.

The views expressed in this book are those of the author although he would like to think that they are representative of the main body of current thinking. The author would not wish anyone to quote opinions expressed in this book as a basis for criticism of others who are no less entitled to their own beliefs and preferences.