The Healing Intelligence of Essential Oils: The Science of Advanced Aromatherapy by Kurt Schnaubelt. 

Exploring science's new biological understanding of essential oils and their advantages over synthetic drugs, renowned aromatherapist Kurt Schnaubelt reveals how the effectiveness of essential oil treatments stems from our common biochemical and cellular heritage with plants. He explains how essential oils preserve plants complex natural life-supporting and immune-building qualities, developed through millions of years of interaction with animals and humans. Reviewing recent research in molecular, cellular, and evolutionary biology, he shows how the multilayered activity of plant essences helps maintain the integrity of our genetic code - the reason why pathogens cannot develop resistance toward essential oils as they do with antibiotics and antivirals - making essential oils a more effective and sustainable form of treatment for a variety of health problems. 

Laying to rest old arguments over essential oils' alleged toxicity and whether or not they can be ingested or used undiluted, Schnaubelt presents simple recipes and protocols for treating and preventing common aliments, such as colds, flu, herpes, liver detoxification, etc.