Most of our existing reliefs have come from tombs. In the mastabas their production was easy enough. The sculptor simply carved the faces of their limestone walls. But in the hypogea the difficulties were frequently great, and yet they were always surmounted. The bas-reliefs in such places were, as a rule, on a small scale. Consequently, the knobs of flint and the petrified shells with which the sculptor's chisel was continually coming in contact, must have embarrassed him in no slight degree. Whereever such unkindly lumps were found, they were extracted from the rock, the rough holes which they left were squared and filled up either with a cement which became very hard with time, or with pieces of stone accurately adjusted. In the latter case, the joints have been made with such care that it is very difficult to discover them. In some tomb chambers these insertions are so numerous that they make up not less than a quarter of the whole surface.[278] [278] _Description de l'Égypte, Antiquités_, vol. iii. p. 42. As soon as the carvings upon the walls were finished, the latter were covered with a thin layer of stucco. This was hardly ever omitted; it was laid upon rock, cement, and limestone indiscriminately. It afforded a better and a more tenacious ground for coloured decoration than the naked stone.[279] [279] BELZONI (_Narrative of the Operations_, etc. pp. 343-365) mentions the presence of this stucco upon the colossi of Rameses at Ipsamboul as well as on the walls of the tombs in the Bab el-Molouk. The principal place in these bas-reliefs is occupied by human figures, and after them by those of animals. The accessories, such as the landscape and inanimate objects are for the most part only slightly indicated, all the labours of agriculture are illustrated, but only so far as the action of man is immediately concerned. There is never more in the way of background than is absolutely necessary for the right comprehension of the scene.[280] The Greeks followed the same rule. In this respect the Egyptians were well advised. Their artistic instincts must have warned them of the true conditions of work in relief, which cannot, without the greatest peril, attempt to rival the complex achievements of painting. [280] This point is very well brought out by RHIND (_Thebes, its Tombs and their Tenants_, etc., pp. 24-25). To this practice we might suggest a few exceptions, in certain chiselled pictures at Tell-el-Amarna, and even Thebes itself, in which the artist seems to have amused himself by reproducing the beauties of nature, of groves and gardens surrounding palaces and humbler dwellings, partly for their own sake, partly attracted by some unwonted aspects of the scene which seem to have been borrowed from neighbouring countries.