"It was, as Berlin remembered it: "The fox knows many things, but the hedgehog knows one big thing." 2 The passage survives only as a fragment, so its context has long been lost. But the Renaissance scholar Erasmus played around with it, 3 and Berlin couldn't help doing the same. Might it become a scheme for classifying great writers? If so, Plato, Dante, Dostoevsky, Nietzsche, and Proust would all have been hedgehogs. Aristotle, Shakespeare, Goethe, Pushkin, and Joyce were obviously foxes. So was Berlin, who distrusted most big things--like logical positivism--but felt fully at ease with smaller ones. 4 Diverted by World War II, Berlin didn't return to his quadrupeds until 1951, when he used them to frame an essay he was preparing on Tolstoy's philosophy of history. It appeared two years later as a short book, The Hedgehog and the Fox. Hedgehogs, Berlin explained, "relate everything to a single central vision" through which "all that they say and do has significance." Foxes, in contrast, "pursue many ends, often unrelated and even contradictory, connected, if at all, only in some de facto way." The distinction was simple but not frivolous: it offered "a point of view from which to look and compare, a starting point for genuine investigation." It might even reflect "one of the deepest differences which divide writers and thinkers, and, it may be, human beings in general."