Let us go then, I and me

Arthur looked around the room nervously. All around it was pink — the room, that is. Something made him uneasy.

"I've just thought of something," said Boffo the Poffo.

Arthur said:
Let us go then, I and me
As the evening sinks fatigued into the sea
Like someone who is really rather bored;
Let us go and then come back again
Muttering, a bit insane
Like one who is temporarily into Zen
(What of two — and who knows when?)
I shall therefore come back and follow me
(Where id was, there shall ego be)
Inquiring after number three
Our other personality.

He was the unbalanced one, you know
Who thought he was Michelangelo.

So Arthur went, and took Lancelot and Boffo with him.