Interesting Facts. Episode 1. Sneezing
When people sneezed in the past, it was considered very bad, for such a person might infect the whole village.
So everybody wanted each other to stay healthy. That's why when anyone showed signs of falling a victim to the cold, they blessed each other, saying 'God bless you!' hoping that God would hear and cure them of this plaguing cold.
Soon the priests admonished them for such words, saying that they must not use the Lord's name in vain, meaning that they shouldn't say 'God' without a very good reason.
So people stopped wishing each other 'God bless you', and started saying simply ' Bless you', which became a tradition.
However, the most recent trend in etiquette tells us that we must not even notice other people's bodies' sounds. So when we hear someone sneeze, we should keep silent and pretend that nothing happened.