In the Satyricon of Petronius (said to have died in 66 AD), passage 51 (on p.64 of the Penguin Classics edition, translated by J. P. Sullivan, ©1965, 1969, 1974, 1977) reads
`Mind you, there was a craftsman once who made a glass bowl that didn't break. So he got an audience with the emperor, taking his present with him. Then he made as though to hand it to him and dropped it on the floor. The emperor couldn't have been more shaken. The man picked the bowl off the ground -- it had been dinted like a bronze dish -- took a hammer from his pocket, and easily got the bowl as good as new. After this performance he thought he'd be taken for God Almighty, especially when the emperor said to him:
` ``Is there anyone else who knows this process for making glass?''
`But now see what happens. When the man said no, the emperor had his head cut off, the reason being that if it was made public, gold would have been as cheap as muck.'