I had initial high hopes of this book. I thought the pictorial view of the chemistry of oils was a wonderful aid to an appreciation of the 'character' of an oil as indicated by its chemical constituents.
However, a rigid application of the 'functional group' theory of chemistry only illustrates the limitations of the approach - for example, Caddy subscribes to the functional group theory which would state that the general action of an alcohol is stimulating, and while she acknowledges that some sesquiterpene alcohols may be sedative in action, she finds herself trapped, by a rigid functional group approach, into, for example, for carrot seed, drawing a pie chart of an oil which is more stimulating than sedative in its actions. I don't think many practitioners would agree with that! Another example is vetiver, which by this 'functional group' analysis shows itself to be a stimulating/balancing oil, rather than a sedative, whereas again this really does not equate with the way most practitioners would view the action of that oil.
These 2 examples are not isolated.
Whilst a close study of chemistry is necessary and useful to the serious student and practitioner, I think it is important to acknowledge that while sometimes a chemical analysis of an oil will precisely explain its actions, the fact that each oil is a synergistic blend of chemical constituents will mean that sometimes the actions of an oil will seem to be completely different from that suggested by its chemistry - there are so many examples of oils in this book which just don't work in the way a rigid functional group approach suggests. German Chamomile as a stimulant, for example? - her explanation of what each oil 'does' is fine enough, I wouldn't quarrel with that - but its the 'pie chart pictures' which are so contradictory - not, I hasten to add, the pie charts themselves, which are great, but the rather doctrinaire interpretation of what they mean.