In nature each plant's tissues are imbued with certain properties. They may be taste, smell or certain effect on the body. Over thousands of years people have observed these and noted them. The tradition goes way back, you may recall the Egyptians using "balms" to treat wounds and embalm the deceased. Aromatherapy, the study of these properties has since evolved to a science by eastern and western herbalists in Herbal Medicine, Chinese Medicine and even in herb/spices in preparation of food.
Over the years much study has gone into researching their qualities and respective uses. As energy (akin to homeopathy) each plant contains and radiates a it's own type of energy and this energy in turn has subtle healing properties. However unlike homeopathic preparations essential oils are very concentrated. In Chinese medicine it is their flavour and how they affect the body that is considered. In this case they may warm or cool, They may move as in stimulate or calm and so on.
As bio-chemical properties where their action may be soothing or protective of body's tissues. They can also aid healing of tissues (think of Lavender oil and burn injuries) and in most cases protect from viruses (Tea Tree oils have now become the disinfectant and staerilisant of choice in a number of hospitals due to it's ability to kill antibiotic resistant bugs.)
At emotive-response level where through stored emotional states that are evoked by smells that our brain has linked to them. The best example is when we arrive home to the smells of a beautiful meal being cooked, baked bread or cake. Almost immediately we are taken back to perhaps our childhood or a time that is special to us. Aromatherapy essental oils use this mechanism to evoke soothing, stimulating and other responses from your tissues and nervous system.
In Chinese medicine they are applied to acupuncture points or channels. It is also possible to use them by diffusing into the air.
The therapeutic process of aromatherapy is linking and applying these healing qualities to your individual needs and suiting particular conditions.
When it comes to Essential Oils, it all starts with the processes of harvesting, extracting and finishing with hot or preferably cold distillation. The plant's most potent parts such as flowers or tips of new leaves are harvested. These are then gathered and in special vessels are brought up to specific temperatures where these oils evaporate. The resulting vapour is then cooled and condensed. The liquid is taken through this cycle a number of times to exclude impurities and thus intensify it's respective healing qualities.
Now why go to the extra trouble of selecting organically grown and processed oils? I mentioned that each plant has it's own specific healing and energetic properties. These are derived in part by it's own genetic code, it's living environment, the care taken in processing it, packaging it and finally applying them to your body. All of these steps have an inherent energetic side too. This can be thought in terms of how we are affected when working near a very angry person or one that is depressed. Weather we like it or not some energy is transferred and our moods are affected and vice versa. When we are having an excellent day we also lift the persons around us.
In terms of synthetic oils, they are cheap for a reason. Chemicals used to emulate the scent and I mean loosely emulate because most don't even come close. Once you have smelled the real natural essential oils you have no trouble detecting the synthetic from real. Their chemical makeup is not even remotely close to the real thing so their effects are at best going to be similar as if we ingested these chemicals i.e. toxic. Now you may say: why would you ingest such a thing. Well you do in a way because though your skin (in the case of a massage) your largest porous organ they do end up in your blood stream and your liver is going to have to work to remove them. At least you hope it does. You will also be smelling them and that is the other path of absorption. Your lungs absorb oxygen from the air and this path is used by cigarettes and other drugs. The plants used for extraction of essential oils are in many cases actual foods, plants like basil, majoram, organo, pepper, ginger, cinnamon and so on. You can taste them and they taste just like food.
What sort of energy is imbued if the plants are chemically sprayed? What sort of energy is bestowed on the plants or indeed the final product if it is exposed for months and months to chemicals or not handled and stored with care..
You are paying to get better so make sure no shortcuts are taken undermining your health further.