In Europe in the middle ages, aromatic plants such as clove, cypress, sage and rosemary were burned in an effort to control plagues. The use of natural oils for both fragrance and healing purposes however started to die out in the early nineteenth century when scientists learned how to synthesize the plant oils for both perfumes and medicines. It was thought that the new synthesized products would take the place of the natural, more expensive substances, which accordingly fell out of favor. Since then of course, we have learned that synthesized drugs do not always provide the best answer and that nature often provides a solution that is more suited to the task and with fewer side-effects. Although the essential oils, which are extracted from plants, have very specific aromas which have been used effectively to cure a wide variety of ailments since the time of the ancient Egyptians.
Essential oils can enter the body through the air via the nose and bronchial passages.
Aromatherapy makes use of both inhalation and absorption. The power of smell is a very powerful trigger to the human nervous system. Some aromas, such as newly cut grass, the sea breeze, etc. have evocative smells so powerful that simply reading the word can remind us of the aroma. An aroma usually has an immediate effect, which is why smelling salts can instantly revive. The nose contains tiny hair-like extensions of the brain which detect scent.