Both men specialised in mixing history and philosophy. Berlin abandoned the analytic philosophy of 1930s Oxford for the history of ideas. He wanted to explore the great issues at the heart of political theory by interrogating the great thinkers rather than play games with words. Trevor-Roper believed, like the 18th-century historians who were his models, that “history is philosophy teaching by example”. He argued that historians should study problems that illuminated the human condition, such as the relationship between religion and social change or the state and the society that supported it. And he believed that historians can make a unique contribution to studying these problems by escaping the tyranny of time and place: he viewed Nazi Germany through the eyes of Tacitus, and McCarthyite America through the eyes of Erasmus.
This mix of worldliness and unworldliness—familiarity with affairs of state coupled with philosophical detachment—holds the key to the continued appeal of both men. They chose to address big subjects rather than solve academic crossword puzzles. They wrote for the educated public, not just cloistered scholars. Berlin produced a stream of essays on great political thinkers ranging from German nationalists to Russian novelists. Trevor-Roper roamed across the centuries: though his first love was the 17th century, he also wrote about Hitler’s Germany, the rise of medieval Europe, and, in one of his liveliest books, an Edwardian fantasist, forger and sex maniac, Sir Edmund Backhouse.
I haven't ever read Trevor-Roper—though I suppose I'll almost be compelled to now—but Isaiah Berlin has always been a joy for me to read. Not quite as succinctly quotable as other favorites ("a formidable polymath, and a prodigious, if donnish, talker," as Arthur once said to me) he's still one of my formative influences. I actually had both John Gray's and Michael Ignatieff's biographies of him on the bedside table when I happened upon this article. Serendipity.