Aromatherapy is the treatment of physical ailment through essential oils which contain natural healing properties derived directly from nature.
Part of the reason why we're suffering ill health more now than at any other time before is because we've become so out of synch with nature. The thing that we used to rely so heavily upon 100 years ago barely gets an afterthought as we reach for the headache or the sinus pill from the medicine cabinet.
Nature is perfect. It just functions in harmony without so much as a second thought, it's we that synthesize and derive all of our medicines from nature's example. We don't have to chemically duplicate what nature has so perfectly created itself. Instead of using treatments with chemicals that were mimicked in nature's image we need to use the ingredients and building blocks taken directly from nature itself.
We generally go for the 'maximum relaxation' essential oils - chamomile, jasmine, lavender, sometimes lemongrass. Prado2spa, you mentioned clary sage, we are cautious with that given its well-documented side effects