The scales and judgment-hall, however, belong to the religious conceptions which gathered round the name of Osiris, like the Paradise which the risen mummy looked forward to enjoy. It was only after the worship of Osiris had become universal throughout Egypt, and the older or local ideas of the future life had been accommodated to them, that it was possible for an Egyptian to speak of meeting his disembodied heart, or of the testimony it could give for or against him before the judges of the dead. The fact that the use of the scarab does not seem to extend further back than the age of the Memphite or Theban dynasties, may imply that it was only then that the Osirian beliefs were officially fitted on to earlier forms of faith. However this may be, the worship of Osiris and the beliefs attaching to it must be left to another lecture, and for the present we must pass on to the mummy itself, the last part of man which it was hoped would be immortal. The mummy or Sâḥu has to be carefully distinguished from the Khat or natural body. The latter was a mere dead shell, seen by the soul but not affording a resting-place for it. The mummy, on the other hand, contained within itself the seeds of growth and resurrection. It could be visited by the soul and inspired by it for a few moments with life, and the Egyptian looked forward to a time when it would once more be reunited with both its heart and its soul, and so rise again from the dead. It is impossible to say how far back in the history of the Egyptian religion this belief in the immortality of the mummy may go. It can hardly have originated in the same circle of ideas as the doctrine of the Ka, though the doctrine of the Ka could easily be reconciled with it. On the one hand, it seems connected, as we shall see, with the cult of Osiris; but, on the other hand, there are no traces of mummification in the prehistoric graves, and it is doubtful whether there are any in the royal tombs of Negada and Abydos which belong to the age of the First and Second Dynasties. At all events, the scarab, which accompanied embalmment, first appears at a much later date, and perhaps had a Memphite origin. There are, however, indications that the process of embalming first arose among the pre-Menic rulers of Nekhen, in the neighbourhood of El-Kab. The soil of El-Kab literally effloresces with the natron, which, it was discovered, preserved the bodies buried in it; and even as late as the time of the Pyramid texts of the Fifth and Sixth Dynasties, when the northern sources of natron were known, it was still necessary for ceremonial purposes that the materials used by the embalmer should contain some of the natron of El-Kab.(38)