What is the origin of the idiom "breathe a word about something" and when to use it?

The idiom "breathe a word about something" originated from the idea that speaking requires the physical act of exhaling breath, and thus, uttering a word implies revealing or disclosing information. The phrase conveys the notion of keeping something secret or confidential by refraining from speaking or sharing information with others. It is primarily used to emphasize the importance of maintaining silence or discretion to prevent the disclosure of sensitive or private matters.