The word luz in Hebrew (Hebrew: 'לוז') means nut or almond. Because of this it became associated with the small bone at the top of the spinal column (the seventh cervical vertebra) or the coccyx, the small bone at the base of the spinal column, depending on the tradition.
Jewish traditions teach that this is the bone from which the body will be rebuilt at the time of resurrection, and share the idea that this bone does not decay. There is an aggadah (legend) in the midrash that the Roman Emperor Hadrian asked how man would be revived in the world to come, and Rabbi Joshua Ben Hananiah replied that it would be "From Luz, in the back-bone." "Prove this to me," said Hadrian. Then the Rabbi took Luz, a small bone of the spine, and immersed it in water, but it was not softened; he put it into the fire, but it was not consumed; he put it into a mill, but it could not be pounded; he placed it upon an anvil and struck it with a hammer, but the anvil split and the hammer was broken. (Ecclesiastes Rabbah xii / Genesis Rabbah xviii).
The luz bone narrative can be linked directly to the human-divine encounter in Ezekiel ch. 37 which alludes to the time of the return of the Jewish People to their land after a long exile. The valley of dry bones, that is, the exile or in a metaphorical sense, human constituent, encounters the immortal spirit of God in Eretz Israel, the land of the living, in contrast to this valley.
- The mystical bone of resurrection, Shapiro R., 1987, Department of Radiology, University of Miami School of Medicine, accessed 5 April 2014 http://pubs.rsna.org/doi/abs/10.1148%2Fradiology.163.3.718#comments
- Sefer Ta'amei Haminhagim. 425.