Essential - essence

"essential oils" is a common phrase among people who deal in aromas. Definitions often say describe something, perhaps an oil, with an aroma that is the product of "distillation".

Does anyone know how the word "essential" got into smell business?

The following from the American Heritage Dictionary's definition of "essence":-

NOUN: 1. The intrinsic or indispensable properties that serve to characterize or identify something.
2. The most important ingredient; the crucial element.
3. The inherent, unchanging nature of a thing or class of things.
4a. An extract that has the fundamental properties of a substance in concentrated form. 4b. Such an extract in a solution of alcohol.
4c. A perfume or scent.
5. One that has or shows an abundance of a quality as if highly concentrated: a neighbor who is the essence of hospitality.
6. Something that exists, especially a spiritual or incorporeal entity.

The word "essence", as can be seen from 4c above, has been used on its own to describe perfumes or scents - essence of rose and so on. Its adjective "essential" is therefore well-used to apply to a range of highly concentrated fragrant oils. Of course, it does absolutely no harm from a marketing point of view that "essential" also has the meaning of "vital to existence".