How do I know that?
because the clever binder, seeing some MS.
remarks on one of the margins, turned the leaf down to avoid cutting them off, and that stern witness will always testify, to the observant reader, the original size of the book.

This same binder, on another occasion, placed a unique fifteenth century Indulgence in warm water, to separate it from the cover upon which it was pasted, the result being that, when dry, it was so distorted as to be useless.

That man soon after passed to another world, where, we may hope, his works have not followed him, and that his merits as a good citizen and an honest man counterbalanced his de-merits as a binder.
Other similar instances will occur to the memory of many a reader, and doubtless the same sin will be committed from time to time by certain binders, who seem to have an ingrained antipathy to rough edges and large margins, which of course are, in their view, made by Nature as food for the shaving tub.
De Rome, a celebrated bookbinder of the eighteenth century, who was nicknamed by Dibdin "The Great Cropper," was, although in private life an estimable man, much addicted to the vice of reducing the margins of all books sent to him to bind.

So far did he go, that he even spared not a fine copy of Froissart's Chronicles, on vellum, in which was the autograph of the well-known book-lover, De Thou, but cropped it most cruelly.
Owners, too, have occasionally diseased minds with regard to margins.

A friend writes: "Your amusing anecdotes have brought to my memory several biblioclasts whom I have known.