"Winning the earth" has been the military ambition of many would-be world rulers. Their method has been conquest by force; gaining ground by shedding blood.
The cut and thrust of business life is all about getting the advantage: mercy is seen as a weakness to be despised, unless it is a way of manipulating people.
Purity is an absolute measure: something is either pure or impure; it cannot be 99% pure … because it is then impure. To be 'pure in heart’ is to be 100% free from sin, and totally pleasing to God.
It has become embedded into the English language: 'salt of the earth' means a good person who is reliable, hardworking, kind and generous. But that was not really what Jesus meant.