7. Arab Glazing in Plaster.
Whence the mediæval Arabs got their glass, and the quality of the material, are matters of conjecture. If we may judge by the not very ancient specimens which reach us in this country, the glass used in Cairene lattices is generally thin and raw; but set, as above described, in jewels as it were, isolated each in its separate shadow cell, the poorest material looks rich. The lattices here illustrated are none of them of very early period; but, where the character of design is so traditional and changes so slowly, the actual date of the work, always difficult to determine, matters little.
8. Arab Glazing in Plaster.
It is more than probable, it is almost certain, that the Venetian glass-workers, who in the tenth century brought their art to France, were familiar with the coloured lattices of the Levant; for, as we know, in the middle-ages Venice was the great trading port of Italy, in constant communication with the East. If that was so, the Italians, always prone to imitate, would be sure to found their practice, as they did in other crafts, more or less upon Persian and Arabian models. At all events, there is every reason to suppose that at first they, practically speaking, only did in lead what the Eastern artificer did in stone or plaster, and that the windows which, according to various trustworthy but vague accounts, adorned the early Christian basilicas as early as the sixth century, bore strong likeness to Mohammedan glass—Christianised, so to speak. This is not to unsay what was before said about the affinity of early glass to enamel. A river has not of necessity one only and unmistakable source; and though we may not be able to trace back through the distant years the very fountain of this craft, we may quite certainly affirm that its current was swollen by more than one side-stream, and that its course was shaped by all manner of obstinate circumstances and conditions of the time, before it went to join the broad and brimming stream of early mediæval art.
One more source, at least, there was at which the early glazier drew inspiration—namely, the art of jewel setting. Coloured glass, as was said a while ago, was itself probably first made only in imitation of precious stones, and, being made in small pieces, it had to be set somewhat in the manner of jewellery. In all probability the enameller himself wrought at first only in imitation of jewellery, and afterwards in emulation with it.
Just as white glass was called crystal, and no doubt passed for it, so coloured glass actually went by the name of ruby, sapphire, emerald, and so on. It is recorded even (falsely, of course) how sapphires were ground to powder and mixed with glass to give it its deep blue colour; indeed, this wilful confusion of terms goes far to explain the mystery of the monster jewels of which we read in history or the fable which not so very long ago passed for it. Stories of diamond thrones and emerald tables seem to lead straight into fairyland; but the glass-worker explains such fancies, and brings us back again to reality.