It’s hard to say when it began, but it’s a nearly worldwide tradition. Check out this page of different salutations: https://en.wikipedia.org/wiki/Response_to_sneezing
My belief is that it’s generally because sneezing in a sign of illness, and illness tended to be more dangerous centuries ago, before antibiotics and when many people had less access to nutrition, consistent heating, sanitation and so forth.
It’s hard to say when it began, but it’s a nearly worldwide tradition. Check out this page of different salutations:
https://en.wikipedia.org/wiki/Response_to_sneezing
My belief is that it’s generally because sneezing in a sign of illness, and illness tended to be more dangerous centuries ago, before antibiotics and when many people had less access to nutrition, consistent heating, sanitation and so forth.