Paper was expensive. The parchment used in most Medieval books was even more so. So why not use all of it? Why leave those big, empty margins? This is something about book designs which spans cultures, by the way. A lot of old Arabic manuscripts have those as well, with lots of blank spaces around the text.
The reason for that is, I think, related to people relating to books differently. See, in actual use, books looked less like this:
And more like this:
For the wealthy, educated book owner, the book wasn’t necessarily left pristine. It was, rather, a working object, a tool for thinking and learning rather than an inviolable object.
私の思うにその理由は、人により本に対して異なっているからだろう。見て下さい。実際、本はあまりこのようには見えない:
むしろこのように見える:
金持ちで学識のある本の所有者にとって、本は必ずしもきれいなものではない。神聖なものというよりは、むしろ使用する目的のもので、考えたり勉強したりするために使うものである。
この理由として、私は様々な方面から人々と本の関係性があると思いました。
見てわかるように実際に本はこのようではなく:
どちらかというとこれらに近いのです:
裕福で教育のされた本の持ち主にとって本は新品の必要はありませんでした。むしろ、神聖なものではなく、仕事上の対象、考え、学ぶための道具として扱われていたのです。
Those huge margins leave room for marginal notes, commentary, glosses on unfamiliar words, and so on. Rather than taking notes on a book on a separate piece of paper/parchment/whatever, a reader would put them in the text itself. All those fancy, pristine books we see on auction or in museums were produced by the same book-making culture which included wide margins as a natural part of book design, but those particular books weren’t used as extensively and were more deliberately preserved, so they give us something of a biased picture of what Medieval books looked like.