Yet despite the lapse of time they retain their freshness and force. This is a tribute to Berlin's style, which conveys an unrivalled depth of learning in prose of engaging informality. A humane light shines through every sentence. It is also a matter of the enterprise he is engaged in: seeing in broad terms how ideas fit together, how one philosophical or political or artistic doctrine gave birth to another, often very different in its tenor. Berlin's genius rests in his capacity to draw the picture with bold outlines, not in technical scholarship. So although his interpretations may be challenged, they are not liable to be displaced merely by the accumulation of new scholarly material.
As with much written at this time, the Cold War and the confrontation between liberalism and totalitarian systems of Right and Left provide the background to these essays. Berlin's hatred of Fascism and Stalinism, and his devotion to personal liberty and freedom of thought, are everywhere apparent, yet they do not distort his reading of past thinkers in the way that, for instance, Karl Popper's treatment of Plato and Hegel was distorted. Why is this? Berlin's attitude to those post-Enlightenment philosophers - Herder, Fichte, Hegel, Marx - whose ideas became associated with totalitarian political doctrines is deeply ambivalent. The revolt against the Enlightenment may eventually have had terrible repercussions, but its core ideas - human beings' need to find authentic forms of self- expression, the irreducible diversity of human cultures - remain central to our own worldview.
Moreover Berlin, Order of Merit and fellowship of All Souls notwithstanding, still is in some respects an outsider. He sympathises with the outcasts and the dispossessed, and with doctrines that express their feelings. He writes here with unexpected charity about the humanist Marxism of the second International, and, in the last essay of the book, about the need for recognition which fuels nationalist movements in colonised and backward countries. Indeed, unlike many liberals who write nationalism off as an infantile disorder, Berlin sees moderate forms of nationalism as expressing a deep-seated human desire for a secure cultural identity that wins the respect of other cultures. His liberalism is more relevant outside a narrow Anglo-American political context than, for example, John Rawls' or Ronald Dworkin's.
Readers new to Berlin will find well expressed here ideas for which he has become justly celebrated: his opposition to historical determinism, and to the idea that human societies can be understood by methods modelled on those of the natural sciences; and the line he draws between thinkers who hold that everything that is valuable in human life can finally be drawn together in one harmonious scheme, and those who hold that there are irresolvable clashes between human values, so that conflict and the need for conciliation must be permanent features of any human society.
The first of these ideas is explored in the title essay, which poses the question: if indeed there are no inexorable laws of history, what does it mean to say that one political project is feasible while another is utopian? Why did Washington or Bismarck, say, achieve their aims while Robespierre or Stalin failed? Berlin's answer is that successful statesmen display a political judgement akin to that of a historian who succeeds in recapturing the distinctive character of a past era. There is a way of understanding how people in a particular time and place think and act which also tells us what can be changed politically and what cannot. This is "the sense of reality" - something quite different from knowledge of sociological laws.
In perhaps the most contentious essay, Berlin claims that philosophers need special protection against governments seeking to suppress freedom of thought. He evokes superbly what is distinctive about philosophical thought: its capacity to shake up the most basic concepts that we use to make sense of our world. But he moves too quickly to the conclusion that great philosophy is bound to have a subversive political impact. What of those philosophers whose political principles have been broadly conservative? Berlin deals with them ad hoc: Aquinas is relegated to the philosophical Second Division; Hume is conveniently overlooked; Hegel, defender of constitutional monarchy, is revolutionised by association. "The Marxist and Fascist consequences of applying certain principles of Hegel (however distorted) are not in doubt. In this sense philosophers are necessarily subversive." The bracketed words testify to Berlin's honesty, but they fatally weaken his case.
Are authoritarian regimes more deeply threatened by freedom for philosophers than freedom for intellectuals of other kinds, historians for instance? In the Soviet Union, was it more subversive to challenge dialectical materialism or to question the official, Trotsky-free story of the Russian Revolution? This would make a splendid topic for one of those prize essays that Enlightenment academies used to propose, and it's just the kind of far-reaching question that Berlin's sparkling essays invite us to ask.
! Dr David Miller is Official Fellow in Political Theory at Nuffield College, Oxford