The advertising agency J. Walter Thompson used to set a test for aspiring copywriters. One of the questions was simple: ‘Here are two identical 25-cent coins. Sell me the one on the right.’ One successful candidate understood the idea of alchemy. ‘I’ll take the right-hand coin and dip it in Marilyn Monroe’s bag. Then I’ll sell you a genuine 25-cent coin as owned by Marilyn Monroe.’
In maths it is a rule that 2 + 2 = 4. In psychology, 2 + 2 can equal more or less than 4. It’s up to you.