Aromatherapists, armed with a technical understanding of an oil's constituents, artfully blend essential oils to produce new aromas. The results of aromatherapy are very individual. While there is general agreement about the actions of certain oils, aromatherapy texts vary in their descriptions of the properties and characteristics of an essential oil. No two persons are affected by the same essential oil in exactly the same way. Even the same person can be affected differently by the same oil depending on surroundings, time of day or mood.
Essential oils are the highly concentrated, volatile, aromatic essences of plants.
Scientists agree that essential oils may perform more than one function in living plants. In some cases they seem to be a part of the plant's immune system. In other cases they may simply be end-products of metabolism. Essential oils contain hundreds of organic constituents, including hormones, vitamins and other natural elements that work on many levels. They are 75 to 100 times more concentrated than the oils in dried herbs.