The Golden Principle is a RULE of conduct that encourages people to treat others with kindness and respect. It is also known as the Golden RULE, which states that one should 'do unto others as you would have them do unto you'. This principle has been around for centuries and is found in many religions and cultures around the world. The crossword solution for the term 'Golden Principle' is 'RULE', which is an appropriate answer given the definition of the term.