When someone reads the opening words of The Social Contract, for example, namely that Man is born free and everywhere is in chains, does he think, “Gosh, that is true, I never thought of that before!” or does he think, “I wish I were free of all the irritating restraints on my behaviour that prevent me from doing exactly as I choose”?

Rousseau was so contradictory that what we take from him depends almost as much on us as on him. He is a kind of lightning conductor for our desires. Democrats see in his concept of “the general will” the notion of popular sovereignty; aspiring dictators see in it something they believe that they embody, a semi-mystical entity that is independent of any individual’s will, much less that of the numerical majority, and of which he is merely the inspired mouthpiece, as it were.

Rousseau was genuinely revolutionary in the way in which he overturned the notion of Original Sin. For most thinkers before him the question was how Man was to be made good, given his bad or imperfect nature; for Rousseau the question was how Man became bad, given his natural goodness (his answer was society). He did not believe in a return to Nature, exactly, but sought the political means to restore Man to his natural goodness. Personally, I think Rousseau was disastrously mistaken in this; in my opinion, the limitation of the bad in Man is infinitely more important and less sinister politically than the search for the good. When you have limited the bad, the good can take care of itself.

Rousseau was also the unwitting founder of the psychology of the Real Me, that is to say of the inner core of each of us that remains immaculate and without sin, however the external person actually behaves. The inner core, the Real Me, is good; what might be called the Epiphenomenal Me, that is to say the one that loses his temper, tells lies, eats too much, etc, is the result of external influences upon him. In this way a monster of depravity may preserve a high opinion of himself and continue his depravity; nothing he can do can deprive him of the natural goodness first espied by Rousseau.

Jean-Jacques was also, in his way, the philosophical progenitor of Facebook, of the notion that we should live our lives in the open, hiding nothing, for concealment is both the symptom and the cause of insincerity, which was one of J-J’s bugbears. He begins his Confessions in a self-congratulatory way: “Here is the only portrait of a man, painted exactly after nature and in all her truth, that exists and probably ever will exist.” The portrait is extremely interesting because Rousseau, whatever his faults, was an extremely interesting man. Who would not be amused by Rousseau’s account of how he became aware as a child of the sexual pleasure to be had by being beaten by a woman? He continues: “To be at the knees of an imperious mistress, to obey her orders, to have to ask her pardon, was for me a very sweet pleasure…”

The problem is that while all men are born equal, they are not all born equally interesting; so the confessional mode does not suit everyone. Besides, and this is what is tragi-comic about him, Rousseau wrote many hundreds of pages about himself but had no self-knowledge. He quarrelled with virtually everybody he ever knew; he even managed to reduce the philosopher David Hume, one of the most equable human beings in the history of the world, known in Paris as le bon David, to absolute fury. Yet never once did Rousseau think, “Maybe it’s not them, maybe it’s me.”

Thus this most fascinating man was the originator of the most characteristic of our modern vices – self-expression without self-examination.