The centerpiece of intelligence gathering is still the human spy. A high ranking enemy official willing to sell his soul for money will always be the backbone of the business. But when does a spy become a spy? He crosses the line when he first receives payment in exchange for doing something he knows is wrong. At that point, he’s committed. A message will be sent to headquarters informing them of the milestone, and after champagne is uncorked both at headquarters and in the field, a letter of congratulations will be sent to the case officer. That letter is known as Greetings.