Evergreen plants are powerful indeed. Cherokee lore tells us that the Great Creator, after creating All Things, had but one thing remaining to be created: The Human Race. In order to procure the necessary energy, Creator asked all creatures and creations to fast for four days (seasons) to send energy back that humans might be created. By the fourth day (season), only the evergreens had enough power left to remain strong and green.
Whereas many essential oils have a shelf life limited to just a few years under even the best conditions, Patchouli actually improves with age; typically, distillers suggest Patchouli has a twenty-year shelf-life. Indeed, I wasn't much of a fan of Patchouli until I encountered the intoxicating fragrance of a vintage Patchouli that was originally distilled over twenty years ago!