In mediæval libraries or monasteries when a book was to be made, vellum leaves were cut into the required size and folded once across the middle. The folded leaves were then fitted inside each other in groups of four (quaternions) or five (quinternions), or whatever other number seemed good to the bookmaker. The leaves were then marked in some slight way so that their order might not be lost, and sent to the scribe to be written upon.
The books count as folios because each original sheet only forms two pages; the fact of their being arranged in groups is accidental, and does not theoretically alter the size of the book. For this the original skin of vellum would have to be folded with certain further divisions, and in the case of early manuscripts this was never done.
Vellum shows a different surface on the flesh side to that on the hair side, and the scribe usually made his rule marks with a blunt style to guide his writing on the hair side, so that on this side the ruled lines are slightly indented, whereas on the flesh side they show as little ridges.
This point is apparently trivial, but if, as seems likely, both Greek and Latin scribes were really very particular and consistent in the way they alternated the two sides of the vellum, then the matter becomes one of much critical importance. Indeed, it has already been of the utmost value in deciding questions as to whether new pages had been added or not to an old book.
Fig. 24.—Quaternion threaded together.
When the scribe had made his rulings he then doubled up his sheets once, and arranged them as he desired with regard to the hair or flesh sides. When a section of four sheets were fitted into each other, so that when pressed together they made a solid gathering, such a gathering is called a “Quaternion,” from which term we derive our word “Quire.” This is a normal state of things, but it is obvious that abnormal arrangements might easily be made, from the insertion of a single leaf to that of an entirely additional section.
Now the question arose of how best to fasten the quaternions together, not only as to themselves but also as to the other quaternions, which together formed the entire book.
As to the quaternion itself, it must have been evident at once that a stitch of thread or fibre run from the innermost fold right through to the outermost would hold the leaves firmly together. It is likely enough that this was done separately at first, and then the binder would have looked at a small heap of such gatherings wondering how best to keep them together, and it would soon occur to any constructive mind to knot the loose ends of the threads together, or else to supply a supplementary cord or cords laid at right angles to the back of the sections on which the projecting ends of the threads might be tied or sewn.
