Berlin saw the totalitarian advances of the previous decades in the East, and their intellectual apologists in the West, as an enormous threat to the Anglo-Saxon tradition of liberty and freedom.His passionate defence of J S Mill's view of liberty, and his attack on the Hegelian conception of it, in Four Essays on Liberty, became the starting point for any modern discussion on freedom, and also helped to revive a subject that had fallen into the doldrums.But he was a true cosmopolitan, as well-known in New York, Jerusalem and Paris as he was in Britain; and, though scarcely a socialite, he was prominent in many corners of society, with a quite remarkable array of friends and admirers.
Baron Guy de Rothschild (a kinsman of Berlin's future wife Aline) encountered Berlin in New York.
"The most immediately striking thing about him was his unconventional appearance," de Rothschild remembered, "his peculiar air of seeming to float in his clothing." In Washington, where he lodged in Dick Heathcoat Amory's basement, Berlin dis covered - to his delight - that women found him attractive.
Berlin's first book, published in 1939, was a study of Karl Marx.
He was commissioned to write the book by H A L Fisher, but only (so Berlin claimed) after it had been offered to Harold Laski, Frank Pakenham and Richard Crossman.
His political views were not, he recalled, pronounced, except for a general support for liberal ideas and progressive forces.