In the long term, it is desirable that the human race, faced with the prospect of extinction on Earth, should prepare an escape route for itself to another inhabitable planet.

Democracy has many enemies, and the terrorist is only one of them.

Human beings are infinitely worth studying, especially the peculiarities that often go along with outstanding gifts.

If you depart from moral absolutes, you go into a bottomless pit. Communism and Nazism were catastrophic evils which both derived from moral relativism. Their differences were minor compared to their similarities.

It is one of the many ironies of this period that, at a time when the intelligentsia were excoriating Mellon for tax-evasion, and contrasting the smooth-running Soviet planned economy with the breakdown in America, he was secretly exploiting the frantic necessities of the Soviet leaders to form the basis of one of America's most splendid public collections

If the decline of Christianity created the modern political zealot - and his crimes - so the evaporation of religious faith among the educated left a vacuum in the minds of Western intellectuals easily filled by secular superstition. There is no other explanation for the credulity with which scientists, accustomed to evaluating evidence, and writers, whose whole function was to study and criticize society, accepted the crudest Stalinist propaganda at its face value. They needed to believe; they wanted to be duped.

The study of history is a powerful antidote to contemporary arrogance. It is humbling to discover how many of our glib assumptions, which seem to us novel and plausible, have been tested before, not once but many times and in innumerable guises; and discovered to be, at great human cost, wholly false.