This reminded me of something I read in a book about perfume.
"Lignin, the stuff that prevents all trees from adopting the weeping habit, is a polymer made up of units that are closely related to vanillin. When made into paper and stored for years, it breaks down and smells good. Which is how divine providence has arranged for secondhand bookstores to smell like good quality vanilla absolute......"[1]
[1] Turin, Luca, and Tania Sanchez. Perfumes: The A-Z Guide. London: Profile, 2009.