Essential oils come from plants—leaves, bark, roots, and flowers. Their purpose is to protect the plant from fungus, bacteria, insects, and slow decay. They are usually steam extracted and the resulting components are concentrated and powerful.
Some of these components have been researched and their medicinal therapeutic properties have been identified. In clinical aromatherapy, essential oils are chosen based on the medicinal actions of the main components; this is a component blending approach. This approach is how a Clinical Aromatherapist chooses what essential oils to use.
Blending is always done with a holistic approach in mind. The chemistry of the essential
oils, which components will offer the medicinal actions required (component blending approach), along with the emotional and energetic aspects of the oils in relation to the person being blending for. The aroma is always a significant part of the blending process as well. The route of application (topical skin application and inhalation), dilution and frequency of use are also important factors.
Considering the whole essential oil, the aroma, energetics, history, and culture along with the chemistry creates a truly holistic approach.