This book is a must have.  It focuses on the active constituents in plants and their synergy.  For example, St. John's wort has been tauted as an antidepressant and often hypericin or hyperforin are put into herbal antidepressant formulas.  However research has reported that hyperforin worked synergistically with hypericin as well as xanthone phloroglucinol derivatives.  This suggests that maybe the whole plant would work better as an anti-depressant formula than just what was thought to be the main constituent.  Also, I have always personally wondered why feverfew hasn't been very effective for headaches when it has anti-inflammatory and migraine preventative properties.  That is because these properties break down quickly once the plant is dried (harvested) so either fresh plant or freeze-dried is necessary.  Or why do "magic mushrooms" make you feel so good?  The active metabolite psilocin is chemically and structurally similar to the feel good neurotransmitter serotonin. 

Ganora also talked about supercritical CO2 extraction which is a newer method to the herbal industry that is used to extract fat soluble constituents without using toxic hexane.  If companies are using this method, they will note it because it makes their product superior. 

This is really a great book for herbalists or practitioners who prescribe herbs.