Always he had endeavoured to view those creatures through their own eyes, and to understand their motivations in terms of their own unique psychologies. Furthermore, he had scored in the 95th percentile in Projective Empathy, thus establishing his raw potentiality for successful extraterrestrial relationships. In a word, he was as prepared for travel as it is possible for a young man to become who has lived all his life in a small town in the hinterlands of Earth.

That afternoon, alone in his attic room, Marvin opened his encyclopedia. It had been his companion and friend ever since his parents bought it for him when he was nine. Now he set the comprehension level at 'simple', the scan rate at 'rapid', punched his questions, and settled back as the little red and green lights flashed on.

'Hi, fellows,' the tapecorder said in its fruitily enthusiastic voice. 'Today – let's talk about Mindswap!'

There followed a historical section, which Marvin ignored. His attention returned when he heard the tapecorder saying:

'So let's just consider Mind as a kinda electroform or maybe even a subelectroform entity. You pro'lly remember from our previous talk that Mind is thought to have begun as a projection of our bodily processes, and to have evolved into a quasi-independent entity. You know what that means, fellas. It means it's like you got a little Man in your head – but not quite. Isn't that quazi?'

The tapecorder laughed modestly at its little joke, then went on:

'So what have we got out of this mishmash? Well, kids, we got ourselves a sort of symbiotic situation, mind and bodywise, even though Mr Mind is inclined to a sort of parasitism. But still, each can exist – theoretically – without the other. Or anyhow, that's what the Big Thinkers say.'

Marvin skimmed.

'Now as for projecting the mind – well, guys, just think of throwing a ball …