"Follow me," the doctor said peremptorily and I followed him, having no idea what was to happen next and why I had ever started it.

Light filtered into the long corridor in which we now were through a skylight high up somewhere. The corridor ended with a tall massive door. The doctor stopped.

"Wait here. Herr Kraftstudt will see you presently."

In about five minutes he opened the door wide for me.

"Well, let's go," he said in the tone of a man who was regretting what was going to happen.

I obediently followed him. We entered a wing with large bright windows and I shut my eyes involuntarily.

I was brought out of my momentary stupor by a sharp voice:

"Why don't you come up, Professor Rauch?"

I turned to my right and saw Kraftstudt in a deep wicker-work chair, the very man whom I remembered so well from the newspaper pictures.

"You wished to see me?" he asked, without greeting me or rising from his desk. "What can I do for you?"

I controlled myself with an effort and went right up to his desk.

"So you have changed your occupation?" I asked, looking hard at him. He had aged in those fifteen years and the skin on his face had gathered into large flabby folds.

"What do you mean, Professor?" he asked, looking me over carefully.

"I had thought, Herr Kraftstudt, or rather hoped that you were still…"

"Ah, I see." And he guffawed.

"Times have changed, Rauch. Incidentally, it's not so much your hopes I am interested in at present, as the reasons that brought you here."

"As you can probably guess, Herr Kraftstudt, I have a fair knowledge of mathematics, I mean modern mathematics. I thought at first you had organised an ordinary computer centre equipped with electronic machinery. However I'm now convinced that this is not the case. In your establishment it's men who solve the problems. As only men of genius would solve them. And what is most strange-with monstrous, inhuman speed. If you like, I presumed to come and meet your mathematicians, who are indeed extraordinary men."