And there was the hat. He picked it up and tried it on. It did not fit very well, no doubt because he was wearing his hair longer now. The hat must be placed where it would be found― Oh, yes, in the control booth. And the notebook, too.
The notebook, the notebook―Mm-m-m― Something funny, there. When the notebook he had stolen had become dog-eared and tattered almost to illegibility some four years back, he had carefully recopied its contents in a new notebook―to refresh his memory of English rather than from any need for it as a guide. The worn-out notebook he had destroyed; it was the new one he intended to obtain, and leave to be found.
In that case, there never had been two notebooks. The one he had now would become, after being taken through the Gate to a point ten years in the past, the notebook from which he had copied it. They were simply different segments of the same physical process, manipulated by means of the Gate to run concurrently, side by side, for a certain length of time.
As he had himself―one afternoon.
He wished that he had not thrown away the worn-out notebook: If he had it at hand, he could compare them and convince himself that they were identical save for the wear and tear of increasing entropy.
But when had he learned the language, in order that he might prepare such a vocabulary? To be sure, when he copied it he then knew the language-copying had not actually been necessary.
But he had copied it.
The physical process he had all straightened out in his mind, but the intellectual process it represented was completely circular. His older self had taught his younger self a language which the older self knew because the younger self, after being taught, grew up to be the older self and was, therefore, capable of teaching.
But where had it started?
Which comes first, the hen or the egg?