From the introduction:
"Groups called Merus started to appear. It´s a play word, or so I was told. The name stuck, and what it really means is a group of people so close together that they help each other to keep it manageable. You don´t remember any of this because you just lost it, but we are part of one. Everyone is, really, but we are in the same Merus, and that´s why I am explaining everything. You probably did the same for me a couple of times before. And you are welcome."
Play requires a large collection of random items, used to drive narrative creation as the items are "remembered".