Eleffantington and Giraffington went to see a couples counselor, a gibbon. She has an office on a second floor with a whiteboard, and the first thing she did was draw on it, reaching the top of the board without getting out of her chair. She drew three pictures.

Each was a point with arrows around it. In the first, every arrow pointed in. In the second, two pointed in and two pointed out. In the third, every arrow pointed out. She said these were the three kinds of critical point, in the technical sense — a place where nothing moves — and that a mathematician would call them a sink, a saddle and a source, and that she had a different name for each.

The sink she called Curiosity. Everything flows toward it. Whatever your partner says, you take in; the gates of both fortresses stand open, and what comes through them arrives. Nothing is repelled at a sink. That is its whole character.

The saddle she called Critique. Along one line, things come in; along the other, they go out. It is open and closed at once. She used the word clopen, which is a real word in topology, and then said something Giraffington wrote down: in a connected space, the only things that are both open and closed are nothing and everything. She let that sit.

The source she called Critical, and then, because Eleffantington asked her to say it plainly, a raid. A raid is an attack and a repel. You go in; what you find pushes you out; everything near the point ends up farther from it than it started. Nothing arrives at a source. That is its whole character too.

Then she said the part that was the session. All three are critical points. All three are places where the conversation stops moving. The question is not which one to live at — a system with only a sink is a system that has quit — but whether you know which one you are standing on when you open your mouth.

Eleffantington said that elephants remember everything and asked whether that helped. The counselor said it was a great many arrows.

Giraffington, who is considerably taller and had been lowering and raising a very long neck throughout, asked whether it was normal to feel faint. The counselor said a giraffe carries a heart of about eleven kilos and a blood pressure roughly double a person's, and that at the base of the skull there is a net of vessels — the anatomists call it a wonder-net — whose only job is to keep the brain from flooding when the head comes down to drink. Bending down to meet your partner's eye, she said, is the most dangerous thing a giraffe does, and it has an organ for it. She did not say what the elephant had.

The counselor sings a duet with her own mate every morning, as gibbons do — the female's part is called the great call, and the male comes in on the coda. She did not bring that up either.

They booked another appointment. On the way out Giraffington lowered his head, and Eleffantington, who takes a long time to turn, waited.