As a child, perhaps you had a Grandmother who was very cuddly and was fond of wearing a particular perfume. She would wrap you up in her arms and hold you close, and make you feel safe and loved and wanted. Can you imagine that if you were to smell that perfume now, that it would invoke those same feelings of safe and calm and loving?
Maybe you have experienced this type of emotional memory linked to an aroma.
In this way, inhalation of essential oils can be used to promote a positive emotional response, such as relaxation. It is amazing how the brain and the body are able to be affected by aroma in such a way!