FOR MY WHOLE generation at Oxford, graduating in the 1950s and 1960s, Isaiah Berlin was, and remains the ultimate model of intellectual excellence, his burning passion for truth and enlightenment suffused with an incandescent glow of breathtaking scholarship, encyclopedic reading and explosive wit. The largest lecture hall in the university was packed twice a week to the rafters with literally thousands of students, many of them playing truant from their proper disciplines and professors.

He was and is a man in whose presence it is impossible to spend even the briefest time, whether sitting at his feet or enjoying his company, without feeling oneself formidably enhanced, twice as intelligent and three times as knowledgeable as one was and really is. He was the ultimate teacher; and yet to those -- and they are legion -- who have been lucky enough to know him personally, he has always been infinitely more than that.

His own pleasure and inspiration has always been found in people and, in particular, in people whom he could admire, honor, enjoy and love. This is what makes Personal Impressions, which is the last of four volumes of his collected essays, such a thrilling and agreeable work.

It records his impressions in about equal measure of three different groups:

the giants of his time -- Winston Churchill, Franklin Roosevelt, Chiam Weizmann and Albert Einstein; the great Oxford figures of his time -- Richard Pares, Hubert Henderson, John Austin, John Plamenatz and Maurice Bowra; and other extraordinary and memorable people whom he encountered -- Lewis Namier, Felix Frankfurter, Auberon Herbert and Aldous Huxley.

Berlin himself defines the essays in this volume as "addresses commemorating the illustrious dead"; and in consequence they have an obituary quality which, nonetheless, escapes banality and rises above hagiography because of the sheer brilliance, understanding and originality of Berlin's writing.

As a small boy, I was brought up on the legend of Berlin by my father, who was Berlin's exact contemporary at All Souls, the pinnacle of Oxford intellectual achievement. I recall in my infancy being told that, while the average Englishman uttered about 250 words a day and the average fellow of All Souls uttered about 10,000 words between dinner and bedtime, Berlin averaged 100,000 words per hour. Berlin was also the man who had laid it down that in America every fact counts for one, no fact counts for more than one and all facts are equal.

To those thus raised both on the astonishing range of Berlin's vocabulary and on the pith of his aphorisms, there is high comedy as well as true tribute in, for example, Berlin's description of his first encounter with Felix Frankfurter.

"Within five minutes . . . a conversation sprang up, about politics, personalities . . . to all of which the unknown professor contributed with such vivacity, and so extraordinary and attractive a mixture of knowledge and fancy, that although I had not intended to stay, I listened (although I am by nature, liable to interrupt) in a state of complete and silent fascination."

Or of his first encounter with that quintessentially English eccentric, Auberon Herbert:

"Some question on my part . . . stimulated him to a magnificent outpouring of words reminiscent in style of an older and more stately world. Although I am far from tactiturn myself, I was, for once, perfectly content to listen. The stream of vivid, somewhat formal, eloquence flowed on like a mountain torrent, carrying all before it."

From this treasury of words and style Berlin draws unstintingly, yet always shunning hyperbole and overworked superlatives, to achieve his purpose, namely to praise famous men of heroic stature for the grandeur, nobility, vitality and humanity which Berlin supremely cherishes and to which he adds no otiose or self-protective qualifications.

Churchill and Roosevelt are his superheroes; and he lets us know it:

"Churchill's dominant category, the single, central, organising principle of his moral and intellectual universe, is a historical imagination so strong, so comprehensive, as to encase the whole of the present and the whole of the future in a framework of a rich and multi-coloured past . . . The units out of which his world is constructed are simpler and larger than life, the patterns vivid and repetitive like those of an epic poet, or at times like those of a dramatist who sees persons and situations as timeless symbols and embodiments of eternal, shining principles. . . .

"As much as any king conceived by a Renaissance dramatist or by a nineteenth-century historian or moralist, he thinks it is a brave thing to ride in triumph through Persepolis; he knows with an unshakable certainty what he considers to be big, handsome, noble and worthy of pursuit by someone in high station, and what, on the contrary, he abhors as being dim, grey, thin, likely to lower or destroy the play of colour and movement in the universe."

And of Roosevelt, whom he never met but clearly admired even more:

"Roosevelt stands out principally by his astonishing appetite for life and by his apparently complete freedom from fear of the future; as a man who welcomed the future eagerly as such, and conveyed the feeling that whatever the times might bring, all would be grist to his mill, nothing would be too formidable or crushing to be subdued and used and moulded into the building of which he, Roosevelt, and his allies and devoted subordinates would throw themselves with unheard-of energy and gusto. . . .

"So passionate a faith in the future, so untroubled a confidence in one's power to mould it, when it is allied to a capacity for realistic appraisal or its true contours, implies an exceptionally sensitive awareness, conscious or half-conscious of the tendencies of one's milieu, of the desires, hopes, fears, loves, hatreds, of the human beings who compose it, of what are impersonally described as social and individual 'trends.' Roosevelt had this sensitivity developed to the point of genius."

While Berlin rises effortlessly to the challenge of grandiloquence where it is apt, he uses simplicity to equal effect on its proper occasions, as in his tribute to the Oxford historian, Richard Pares:

"He had a tender social conscience; he respected earnestness and public spirit; he was very just; he was a willing and life-long slave of self-imposed obligations; and in consequence wore himself out by his devotion to research, his pupils, and later his service to that state . . . He was the best and most admirable man I have ever known."

Berlin also has the very unacademic ability to see the big virtues that lurk beyond the petty faults of even his most contumacious colleagues, as in his tribute-by-anecdote to the philosopher John Austin:

"I asked [Austin]: 'Supposing a child were to express a wish to meet Napoleon as he was at the Battle of Austerlitz, and I said "It cannot be done", and the child said "Why not?", and I said "Because it happened in the past, and you cannot be alive now and also 130 years ago and remain at the same age."' . . . Austin replied: 'Do not speak so. Tell the child to try and go back into the past. Tell it there is no law against it. Let it try. Let it try, and see what happens then.' It seems to me now, as it seemed to me before the last war, that Austin understood the nature of philosophy, even if he was over-pedantic and over-cautious and insisted on making over-sure of his defences before plunging into the arena -- understood, better than most, what philosophy was."

And, again, Berlin could both cherish the Oxford world, of which he was so archetypal a part, and still stand apart from it and see its weaknesses with a clear, if affectionate, eye:

"One of the shortcomings of these meetings is something that seems to me to apply to Oxford philosophy in general, at least in those days. We were excessively self-centred. The only persons whom we wished to convince were our own admired colleagues. There was no presure upon us to publish. Consequently, when we succeeded in gaining from one of our philosophical peers acceptance or even understanding of some point which we regarded as original and important, whether rightly or, as was more often the case at any rate with me, in a state of happy delusion, this satisfied us completely, too completely. We felt no need to publish our ideas, for the only audience which was worth satisfying was the handful of our contemporaries who lived near us, and whom we met with agreeable regularity. . . . This was vain and foolish and, I have no doubt, irritating to others. But I suspect that those who have never been under the spell of this kind of illusion, even for a short while, have not known true intellectual happiness."

Berlin's essays can thus be warmly commended to any reader who is depressed by the sourness of the present age; by its worship of mediocrity and its fear of excellence; by its disparagement of high principles and noble causes and by its elevation of the prosaic, the ordinary, the thin, the gray and the trite into demotic idols; by the substitution of facile cynicism for conscientious skepticism; and by the barbarian prejudice that men only acquire stature by belittling and downing other men. These symptoms of a mean-spirited and fearful age that feels threatened by any exceptional talent or achievement stand out all the more disagreeably against the clear light of Berlin's celebration without shame of fine men, fine actions and fine aspirations.