It used to be that paper was made from rags, a shortage of which gripped the Western world in the early nineteenth century. In Nova Scotia, a young logger and poet named Charles Fenerty proposed a solution: Why not make paper out of wood? (Rags have to be made; trees grow.) “I entertain an opinion that our common forest trees, either hard or soft wood, but more especially the fir, spruce, or poplar, on account of the fibrous quality of their wood, might easily be reduced by a chafing machine, and manufactured into paper of the finest kind,” he wrote in 1844.

Fenerty died in 1892 without ever having secured intellectual property rights to, or a following for, his notion. It took German mechanic Friedrich Gottlob Keller to actually develop a machine that realized Fenerty’s vision. Keller sold his invention to an entrepreneur; a patent was granted; an industry was born.

For a while, the process was unidirectional. Wood was pulped into paper for books, but books were rarely turned back into blank sheets. That changed during the First World War, when the U.S. government, hard up for raw materials, inaugurated the Waste Reclamation Service. As of last count, according to the Green Press Initiative, about 13 percent of the paper fiber in new books is from old books and other recycled sources.