The earliest transcribers of MSS., that is to say, publishers of books, the monks, not only transcribed MSS., but they sold their copies, the sale of books forming part of the monastic revenues. These books were either plain copies for common use, as the service books and the school books, or they were illuminated, bound with decorations of gold and silver, costing very large sums. When, however, as happened in the fifteenth century, the demand for books increased, while the revenues, and therefore the numbers, of the religious in the monasteries decreased, the multiplication of books fell into the hands of laymen. In some cases the monks themselves employed laymen as transcribers. There grew up various branches of the book trade: the maker of parchment, pens, ink, colours for illumination; the writers, the binders, the illuminators, and the sellers. As regards the value of books at any time, it is impossible to estimate it, because we must first learn the purchasing power of money, which is very difficult to ascertain; _e.g._ the price of wheat, sheep, fowls, etc., is a very fallacious test, because we do not know the standards of the time. The wage test is the safest guide. For instance, six pounds a year was thought sufficient pay for the maintenance of a chantry priest—a man considered superior to the ordinary craftsman, yet not very high in the social scale. In addition we must know the whole conditions of production; the cost of materials, the time taken by transcribers for a page or a sheet, the demand, the competition, and everything else connected with the work. Some of these points have been cleared up, but most of them can never be cleared up. It must be sufficient to understand that there was a large demand for books, and that many collections of books were formed by princes and prelates and monasteries. It was a providential circumstance that the art of printing was well advanced at the time of the Dissolution of the Religious Houses. Otherwise the losses, which were great indeed, might have been very much greater, even irreparable.