The preparation of this gold pigment was a very slow and laborious matter. The severe Cistercian rule regarded this process as a waste of precious time; and indeed the use of gold in any form was prohibited in the manuscripts used in Cistercian Abbeys. In the dialogue between a Cistercian and a Cluniac monk, _De diversis utriusque ordinis observantiis_ (_Thesaur. Nov. Anecdot._ Vol. V. 1623), the Cistercian asks "what use there can be in grinding gold and painting large capitals with it"; _aurum molere et cum illo molito magnas capitales pingere litteras, quid est nisi inutile et otiosum opus_? St Bernard himself had an even stronger objection, not only to gold in manuscripts, but to any ornaments with grotesque dragons and monsters, on the ground that they did not tend to edification. _Fluid silver._ _Fluid silver_ was prepared and applied in the same way, but it was much less used than gold pigment. A very beautiful effect is produced in some of the gorgeous Carolingian manuscripts by using in the same ornament both gold and silver, which mutually enhance each other's effect by contrast of colour. _Leaf gold._ _Mordant ground._ _Burnished Gold leaf._ The extraordinary splendour of effect produced by skilfully applied gold leaf depends mainly on the fact that it was laid, not directly on to the vellum, but on to a thick bed of a hard enamel-like substance, which gradually set (as it got dry) and formed a ground nearly as hard and smooth as glass; this enabled the gold leaf laid upon it to be burnished to the highest possible polish, till in fact the gold gave a reflexion like that of a mirror. This enamel-like ground, or _mordant_ as it was called, was commonly as thick as stout cardboard, and its edges were rounded off, which has the double result of making the gold leaf laid upon it look not like a thin leaf, but like a thick plate of gold[254], and at the same time the rounded edges catch the light and so greatly increase the decorative splendour of the metal. _Convex surface._ Thus, for example, the little bosses and studs of gold, which are strewn so thickly among the foliage in the illuminated borders of Italian manuscripts of the fourteenth and fifteenth centuries, are convex in shape, like an old-fashioned watch-glass, and each boss reflects a brilliant speck of light whatever the direction may be in which the light falls upon the page. Perhaps the most sumptuous use of gold leaf is to be seen in some of the early fourteenth century French manuscripts, in which large miniatures are painted with an unbroken background of solid-looking burnished gold, with a mirror-like power of reflexion. It was only by slow degrees that the illuminators reached the perfect technical skill of the fourteenth century in their application of gold leaf. _Purity of the gold._