"It is death to read it," they said.

After that Serge came each day and got books from Halfoff
and Kwitoff. At night he read them. They fired his brain.
All of them were forbidden books. No one in Russia might
read them. Serge read Hamblin Smith's _Algebra_. He read
it all through from cover to cover feverishly. He read
Murray's _Calculus_. It set his brain on fire. "Can this
be true?" he asked.

The books opened a new world to Serge.

The brothers often watched him as he read.

"Shall we tell him everything?" said Halfoff.

"Not yet." said Kwitoff. "He is not ready."

One night Serge went to the room of the two brothers.
They were not working at their books. Littered about the
room were blacksmith's tools and wires, and pieces of
metal lying on the floor. There was a crucible and
underneath it a blue fire that burned fiercely. Beside
it the brothers worked. Serge could see their faces in
the light of the flame.

"Shall we tell him now?" said Kwitoff. The other brother
nodded.

"Tell him now," he said.