There is a line among the fragments of the Greek poet Archilochus which says: 'The fox knows many things, but the hedgehog knows one big thing." Scholars have differed over the correct interpretation of these dark words, which may mean no more than that the fox, for all his cunning, is defeated by the hedgehog's one defense. But, taken figuratively, the words can be made to yield a sense in which they mark one of the deepest differences which divide writers and thinkers, and, it may be, human beings in general. For there exists a great chasm between those on one side, who relate everything to a single central vision, one system, less or more coherent or articulate, in terms of which they understand, think and feel - a single, universal, organizing principle in terms of which alone all that they are and say has significance - and, on the other side, those who pursue many ends, often unrelated and even contradictory, connected, if at all, only in some de-facto way, for some psychological or some physiological cause, related to no moral or aesthetic principle. These last lead lives, perform acts and entertain ideas that are centrifugal rather than centripetal; their thought is scattered or diffused, moving on many levels, seizing upon the essence of a vast variety of experiences and objects for what they are in themselves, without, consciously or unconsciously, seeking to fit them into, or exclude them from, any one unchanging, all embracing, sometimes self contradictory and incomplete, at times fanatical, unitary inner vision. The first kind of intellectual personality belongs to the hedgehogs, the second to the foxes; and without insisting on a rigid classification, we may, without too much fear of contradiction, say that, in this sense, Dante belongs to the first category, Shakespeare to the second; Plato, Lucretius, Pascal, Hegel, Dostoevsky, Nietzsche, Ibsen, Proust, are in varying degrees, hedgehogs; Herodotus, Aristotle, Montaigne, Erasmus, Moliere, Goethe, Pushkin, Balzac, Joyce are foxes.

Of course, like all oversimple classifications of this type, the dichotomy becomes, if pressed, artificial, scholastic and ultimately absurd. But if it is not an aid to serious criticism, neither should it be rejected as being merely superficial or frivolous; like all distinctions which embody any degree of truth, it offers a point of view from which to look and compare, a starting point for genuine investigation. Thus we have no doubt about the violence of contrast between Pushkin and Dostoevsky; and Dostoevsky's celebrated speech about Pushkin has, for all its eloquence and depth of feeling, seldom been considered by any perceptive reader to cast light on the genius of Pushkin, but rather on that of Dostoevsky himself, precisely because it perversely represents Pushkin - an arch-fox, the greatest in the nineteenth century - as being similar to Dostoevsky, who is nothing if not a hedgehog; and thereby transforms, indeed distorts, Pushkin into a dedicated prophet, a bearer of a single, universal message which was indeed the center of Dostoevsky's own universe, but exceedingly remote from the many varied provinces of Pushkin's protean genius. Indeed, it would not be absurd to say that Russia literature is spanned by these gigantic figures - at one pole Pushkin, at the other Dostoevsky; and that the characteristics of other Russian writers can, by those who find it useful or enjoyable to ask that kind of question, to some degree, be determined in relation to these great opposites. To ask of Gogol, Turgenev, Blok how they stand in relation to Pushkin and Dostoevsky leads - or, at any rate, has led - to fruitful and illuminating criticism. But when we come to Tolstoy, and ask this of him - ask whether he belongs to the first category or the second, whether he is a monist or a pluralist, whether his vision is of one or of many, whether he is of a single substance or compounded of heterogeneous elements - there is no clear or immediate answer. 

-From Russian Thinkers by Isaiah Berlin (The hedgehog and the fox: An essay on Tolstoy's view of history)