peoples of these countries remained; and, as we are now aware, carried
on their traditional craft, though in a less splendid way. There is
abundant evidence that pottery was made in the Egypt of Roman times and
later with rich turquoise blue and yellow glazes, though the potters had
learned to produce this glaze on a material containing more clay and
less sand than that used in earlier days. We know also that they had
learned that the addition of lead oxide to a glaze enabled such glaze to
be applied on vessels formed from clay which was sufficiently plastic to
be shaped on the wheel. This knowledge was not confined to Egypt, but
appears to have been spread over Syria and parts of Asia Minor; and
throughout the Byzantine empire many forms of pottery were made which
were clearly the starting-points of much of the fine pottery produced in
Europe in later times. We find, for instance, side by side, a
manufacture of bowls, dishes and vases of very simple shape, yet made of
two distinct materials: (1) a whitish sandy body on which turquoise
blue, green or even white glaze, consisting mainly of silicates of soda
and lime, was used either without ornament or with simple painted
patterns in black or cobalt blue under the glaze; (2) similar vessels
made of a lightish red clay, also rather sandy and porous, coated with a
white slip (pipeclay or impure kaolin) covered with a yellowish lead
glaze. These vessels were decorated in a variety of ways: (1)
_Graffiati_; patterns cut or scratched through the coating of white slip
while it was still soft, down to the red ground, so that when the vessel
was glazed it displayed a pattern in dark upon a light ground. (2)
Yellow and red ochre and copper scales were rudely "dabbed" over the
white slip surface, so that when the vessel was glazed it presented a
marbled or mottled appearance with touches of red, yellow, brown or
green, on a yellowish-white ground. (See the section on _Egyptian
pottery_ above.) (3) Oxides of copper or iron were added to the lead
glaze, and the resulting green or yellow glazes were applied to plain
vases or to vessels decorated with moulded reliefs. In all these methods
we see the continuation of old tradition in simpler forms, but we shall
also see that these, in their turn, became the starting-point of much of
the medieval pottery of Europe, particularly of Italy and the other
southern countries.

In the same way, a little farther east, the Persians of Sassanian t