Whatever it was that Carroll learned it was there and stuck tight. Whether valid or useless it was there. It seemed useful but he could not tell.
For instance there was a concept of a circlet of silvery wire. This was mounted on a small cylindrical slug of metal that enclosed a bimorph crystal. The picture concept showed contour surfaces of force or energy that grew progressively fainter as they retreated from the circlet of wire.
Not magnetism—for Carroll could see no energizing current. Not electrostatic field—for there could be no gradient. The word-concept for the thing was "Selvan thi tan vi son klys vornakal ingra rol vou."
Well—whenever Carroll knew words he would know what the circlet of wire did—and why.
But as he drew the diagram on a sheet of paper and labeled each part with a Terran symbol-system representing the alien sounds Carroll understood one other thing. No book is complete without an index!
Wire recordings of text books are impractical otherwise. An engineer seeking information on the winding, packing fraction of a certain type of wire would not care to wade through four hours of facts. Of course he should know it already, for the facts would be indelibly impressed upon his mind.
But there was the forgetting-factor that comes from disuse of any fact and doubtless this automatic means of education did not forever endow the owner with an eidetic memory of everything—never to be lost no matter how long the facts lie in disuse. But every text book has an index.
And so Carroll sought the laboratory again that night and selected another roll at random. He placed it in the machine and, as he started it, hurled a thought into the machine.
Not words, but mere concept—the abstract idea of listing hurled into the machine and the wire reel sang swiftly through the machine to slow down at a listing.
Useless, of course—there were things like, "Walklin—norva Kin. Fol sa ganna mel zin." Chapter and verse, probably. What Carroll sought was a dictionary.