The cell door slammed behind Rubishov.

Of all forms of mental activity, the most difficult to induce even in the minds of the young, who may be presumed not to have lost their flexibility, is the art of handling the same bundle of data as before, but placing them in a new system of relations with one another by giving them a different framework, all of which virtually means putting on a different kind of thinking-cap for the moment. It is easy to teach anybody a new fact...but it needs light from heaven above to enable a teacher to break the old framework in which the student is accustomed to seeing.

In the pun, two strings of thought are tangled into one acoustic knot.

Creativity in science could be described as the act of putting two and two together to make five

The 'gallows' are not only a symbol of death, but also a symbol of cruelty, terror and irreverence for life; the common denominator of primitive savagery, medieval fanaticism and modern totalitarianism.

Most of us were not afraid of death, only of the act of dying; and there were times when we overcame even this fear. At such moments we were free-men without shadows, dismissed from the ranks of the mortal; it was the most complete experience of freedom that can be granted a man.

Hitherto man had to live with the idea of death as an individual; from now onward mankind will have to live with the idea of its death as a species.