Smell is often the first means by which people become accustomed to aromatherapy, and it is also one of the most effective and enjoyable. 

Smell has a powerful effect on the mind and body and is the sense most often linked to memory.  Inhalation is the quickest method by which essential oils enter the body and take effect. When these pass over minute hairs called cilia a signal is transmitted from the receptor cells to the olfactory bulb and then to the limbic system in the brain. Various chemicals (including important hormones) are then released by the brain which effect the body mentally and/or physically.