In the beginning, people would have to get their perfumes and fragrances from plant and animal sources.
But in the 1800's, the first synthetic fragrance material was produced, and from then on, perfumes were no longer just for the rich. Perfume houses popped up everywhere, and availability to everyone became much easier and cheaper.
As perfumers were becoming popular, secrecy became a MUST. Formulas for fragrance oils couldn't be patented, so listing ingredients on the perfume would have the risk of other companies copying the perfumer's own creation.There is actually a law called the "trade secret" law that gives perfumers the benefit of not having to list their formula and ingredients on their product. However, you can always contact your supplier of fragrance oils and ask for a Material Safety Data Sheet (MSDS). This will give you information on safety precautions, and physical and health hazards.