Two eyes live forever
Two separate eyes are a charter of permanent life. To capture such a group the opponent must fill both eyes, but filling the first is suicide — the move has no liberties and captures nothing, since the group still breathes through the second eye. The suicide rule from 1.6, which looked like a technicality, turns out to be the foundation stone of all life and death: Chapter 8 is simply this lesson grown up. Here the group encloses a straight three of empty points; one move in the middle splits it into two eyes forever. Black to play: make this group immortal.