Origin and Application:
The phrase comes from the sermon which Jesus delivered on Mount Beatitudes in front of a crowd. Salt in the Bible has a special meaning. As much as it is a condiment that gives taste, its harmonizing effect with food makes it a metaphor for friendship and unity. That is why Jesus said, “Have salt in yourselves, and be at peace with each other.” (Mark 9:50)
Salt of the earth is commonly seen in Western literature since its appearance in Wycliffe’s English translation of the Bible. Geoffrey Chaucer, author of The Canterbury Tales, and George Bernard Shaw used this idiom in their literary works. The Rolling Stones released a namesake title which glorifies everyday heroes.