This Twitter thread is a persuasive argument that most — if not all — of the important parts of European civilization are built on ham and cheese, and that includes books, which were originally printed on vellum, a material made from the skin of young male sheep and cows (females being too valuable for breeding). Hardback books were invented because vellum tended to buckle and ripple, so boards were sewn into the cover to keep them straight. Furthermore, books also were built on snails.