Did we need Freud to tell us that we disguise and prettify our motives even to ourselves? Hardly, yet perhaps his itemisation of self-deception—repression, rationalisation, displacement, projection, denial—helps us to pinpoint, and therefore preempt or reform, our unconscious strategies. Perhaps it would have helped the protagonists of Rousseau's Dog to do so also. For the saddest thing about this account of the quarrel between philosophers David Hume and Jean Jacques Rousseau is not that Rousseau should prove himself self-dramatising and hysterical (we always knew he was that) but that dear ‘bon David’ should.turn out to be so blind to his own feelings and motives, ready to buff up what he'd done till it seemed to shine with good intentions. Yet the problem with this fascinating account is its inadvertent anachronism in failing to sufficiently adjust its own inevitably post-Freudian lenses and opprobrium, or position itself with the pre-Freudianism of its protagonists. The book ends by rueing how Hume ‘seemed fixed on demonstrating that reason was indeed the slave of the passions.’ A wonderful irony, but its full piquancy can only be savoured if we realise that the dethroning of reason and blazoning of passion means something different to us reading it in the 21^st century than it would have done to Hume writing it in the 18^th—and partly because he proved to be influential in a way he would not have intended or foreseen.

Hume was using ‘passion’ in its 18^th century sense of ‘emotion’, which is why he could talk about ‘calm passions’, such as love of children, being virtually indistinguishable from reason. Nonetheless, he urged that, in morality, reason not only is, but should be, slave to feeling, since reason can never galvanise us to action whereas the sympathy we instinctively feel can. It merely needs to be extended into a more impartial benevolence for those outside the family and friends with whom we naturally sympathise. When, in 1766, Hume escorted Rousseau (exiled from France and Switzerland) to England, and let him stay for two weeks, before finding him a house in Chiswick, he was acting on the sort of benevolence he advocated. But it seemed as if there might also be a natural sympathy between them. In letters to their mutual French patron, they professed to admire one another's work, and each exalted the other's ‘genius’ and virtue, Hume praising Rousseau's ‘greatness of mind, which makes him fly obligations and dependence’, while Rousseau declared that Hume's ‘impartiality’ as a historian enabled him to survey ‘in every point of view, what passion has not permitted me to contemplate but from one side’.

Flowery insincerity to modern ears, but Edmonds and Eidinow never comment on that, or perhaps rightly discount for standard 18^th century politesse.Yet they do not allow such latitude when meticulously analysing disingenuousness and hyperbole in the letters Hume wrote after the friendship so fulsomely pledged was ruined. Of course they do not dispute that Rousseau was being characteristically paranoid when accusing Hume of being part of a plot against him, and Hume does not prove entirely blameless—he secretly investigated Rousseau's finances, and possibly laughed at him behind his back. But can Hume be held culpable for failing to provide the passionate (in a modern, if non-sexual, sense) love that Rousseau craved, rather than dutiful benevolence? What really rankled with Rousseau was the very impartiality he had once praised, as is wonderfully conveyed in an episode reconstituted from its participants' tellingly con-and diverging accounts. After an evening of sullenness on each side, Rousseau suddenly sat down on Hume's knee, throwing his arms around Hume's neck and kissing him warmly while ‘bedewing all my face with tears’. In Rousseau's account, Hume responded by merely patting him on the back with ‘a few cold strokes’, and exclaiming ‘over and over again, “My dear Sir! What is it, my dear Sir?”’ whereas Hume claims to have been ‘melted’ and to have ‘kissed and embraced him twenty times, with a plentiful effusion of tears’.

It is in such scenes, as in the brilliant description of Garrick's riotous theatre, that the book really comes alive, and we get a full-blooded sense of the 18^th century, but some of its polished ribaldry and exuberant wit is missed. Perhaps Hume was indeed informant, even contributor, to the spoof letter Horace Walpole sent to Rousseau, but, unlike Rousseau, Hume was capable of humour and hilarity (a pity he never hit it off with Dr Johnson) as well as cruelty. This philosopher of the Scottish Enlightenment, chronicler of English history, urbane diplomat and friend of Adam Smith always remained an exemplar of Classicism, holding onto the over-optimistic notion that people could be rational, transparent and amenable to reason. Rousseau, with his incomprehensible inconsistencies on the general will and the noble savage, is an obvious influence on the French Revolutionaries, the Romantics and our contemporary psychobabblers. Yet, oddly, it may be that Hume's more argued-out, rational, intellectual theorising contributed more to dethroning reason (so long upheld as the special, sacred feature of humanity that raises us above the animals) to something we ‘possess in common with beasts’, and ‘nothing but a species of instinct’.