...in Pliny's time, it was believed that only the blood of a newly sacrificed kid, or lamb, could shatter a diamond. Pliny wondered--as many did until the seventeenth century when this 'fact' was still being quoted as a gemological curiosity--how anyone could have thought to experiment with such a thing ... He did not realize that the story was probably a metaphor, perhaps with the same root as the Christian symbol of the Lamb of God. A diamond is the hardest substance; a sacrificed lamb or goat the most innocent. The only way to overcome harshness and brutality, the imagery suggests, is with love.