Plants all over the world are growing and producing living agents that help benefit the life of the plant as well as benefit us if we utilize it. Agents/substances that deter viruses, bacteria or parasites that would hurt the plant. Agents and substances that make predators of any kind (worms, insects, rabbits etc..) avoid the plant. Agents/substances that attract other living life forms (good bacteria, butter flies or bees to pollinate, or any other natural being to help it's existence). These agents (chemical components) are what we are going to utilize from the plant to better help our existence. Detoxifying qualities/agents of these oils. Preventive nature of fighting virus, bacteria and fungi. The essence nature of smelling good to uplift our moods or attract feelings/people we enjoy. Like the butterfly we want near us or the ass hole we want far from us. Each plant has varying properties. Some attract, some avoid, some balance, some help communicate signals and so forth. Our job with help of science is to better understand how these mechanisms built right into plants react with and similarly affect our bodies.
How, when, where, why!
If you read my description or tyraid on science, medicine or society you might be turned off or even think i'm a hypocrite using science to explain benefits of oils. That's cool judge away at me, just use the oils for your benefit!