The Celts never took to writing. Even though writing was a thing they knew about, unlike Sumerians they chose to continue maintaining their traditions orally, and as it happens they enjoyed fighting, a chance to prove worthiness so you get the sense that agreements were matters of honor and decency, not contracts. A visceral matter, not a search for loopholes in the law, or lost homework. Cheating was as clear and apparent in those days as it is today, but today glory is gold plate, the difference between winning and losing avoids the awkwardness of honor and keep in mind bear baiting, a favorite sport of both King Henry VIII and Queen Elizabeth I, is currently an illegal blood sport.