This is an an excellent book!
W,S,M describes the three basic personality types, and how we've inherited from our ancestors (Ancestral Memory)
This is NOT about actual memories of the past (ala past life regression) but is about pre-programmed responses to given situations, and how they can reveal your personality type. Thus by understanding these responses we can learn to balance ourselves and actually adopt whichever personality type is best suited to a situation, rather than responding according to our 'type' which may prove unhelpful in certain situations.
Mr. Watts' book gives both the theoretical background, and practical advice, in recognising the three types, both within the people around you and within yourself.