The custom of saying 'God bless you' after a sneeze began as a prayer for survival during the plague.

The origin of saying 'God bless you' is most frequently linked to the Plague of Justinian and the subsequent outbreaks in the 6th century. In 590 CE, Rome was devastated by a plague epidemic that claimed the life of Pope Pelagius II. His successor, Pope Gregory I, also known as Gregory the Great, issued a papal decree commanding the faithful to pray for divine protection. During this era, sneezing was often the first sign that a person had contracted the plague, which was almost always fatal. The Pope instructed that any person who sneezed should be immediately greeted with the phrase 'God bless you' to act as a brief prayer for their soul. This was part of a larger effort to combat the pestilence through spiritual devotion and public litanies. At the time, many people also believed that the soul could be accidentally expelled from the body during a sneeze. Others thought that sneezing opened the body to evil spirits or that the heart momentarily stopped during the act. The blessing served as a safeguard against these perceived spiritual and physical dangers. Historical records from the medieval period show that the practice spread rapidly across Europe as the Black Death continued to resurface. While modern medicine has replaced these superstitions with the germ theory of disease, the linguistic habit remains deeply ingrained in global culture. Today, it is viewed more as a gesture of politeness than a religious plea for health.