Sense of smell..

Smell was the first sense that animal life developed and is also known as the most nostalgic sense. A particular fragrance can remind you of an experience in your past. Smell takes a direct route to the limbic brain. It is there that emotional memories are processed and where stress hormones do serious damage.
The sense of smell is the first sense to diminish in older folks. Unlike most senses,molecules of the object detected come in contact with the brain. Many of the essential oils create different emotions within the brain
and thus different consequences.