Then, as the tomb became larger, to accommodate the more abundant offerings, almost every conceivable device was tried to protect the body from such contact. Instead of the goat-skin or matting, in many cases the same result was obtained by lining the grave with series of sticks, with slabs of wood, with pieces of unhewn stone, or by lining the grave with mud-bricks. In other cases, again, large pottery coffins, of an oblong, elliptical, or circular form, were used. Later on, when metal implements were invented (=90=), and the skill to use them created the crafts of the carpenter and stonemason, coffins of wood or stone came into vogue. It is quite certain that the coffin and sarcophagus were Egyptian inventions. The mere fact of this extraordinary variety of means and materials employed in Egypt, when in other countries one definite method was adopted, is proof of the most positive kind that these measures for lining the grave were actually invented in Egypt. For the inventor tries experiments: the borrower imitates one definite thing. During this process of gradual evolution, which occupied the whole of the Pre- and Proto-dynastic periods, the practice of inhumation (in the strict sense of the term) changed step by step into one of burial in a tomb. In other words, instead of burial in the soil, the body came to be lodged in a carefully constructed subterranean chamber, which no longer was filled up with earth. The further stages in this process of evolution of tomb construction, the way in which the rock-cut tomb came into existence, and the gradual development of the stone superstructure and temple of offerings—all of these matters have been summarised in some detail in my article on the evolution of megalithic monuments (=94=). What especially I want to emphasize here is that in Egypt is preserved every stage in the gradual transformation of the burial customs from simple inhumation into that associated with the fully-developed rock-cut tomb and the stone temple. There can be no question that the craft of the stonemason and the practice of building megalithic monuments originated in Egypt. In addition, I want to make it quite clear that there is the most intimate genetic relationship between the development of these megalithic practices and the origin of the art of mummification.