"Just a minute," I said, "I remember now. I was not on my level--that
was not my book store."

"The card orders me to call up the hospital," said the guard.

"It is unnecessary," I said. "Do not call them."

The guard gazed first at me and then at the card. "It is signed by a
Lieutenant and you are a Captain--" his brows knitted as he wrestled
with the problem--"I do not know what to do. Does a Captain with an
affected memory outrank a Lieutenant?"

"He does," I solemnly assured him.

Still a little puzzled, he returned the card, saluted and was gone. It
had been a narrow escape. I got out my atlas and read again the rules
that set forth my right to be at large in the city. Clearly I had a
right to be found in the medical level--but in trying to buy a book
there I had evidently erred most seriously. So I carefully memorized the
list of shops set down in my identification folder and on my cards.

For the next few days I lived alone in my apartment unmolested except by
an occasional visit from Holknecht, the laboratory assistant, who knew
nothing but chemistry, talked nothing but chemistry, and seemed dead to
all human emotions and human curiosity. Applying myself diligently to
the study of Armstadt's books and notes, I was delighted to find that
the Germans, despite their great chemical progress, were ignorant of
many things I knew. I saw that my knowledge discreetly used, might
enable me to become a great man among them and so learn secrets that
would be of immense value to the outer world, should I later contrive to