A great number of excellent and pointed half-truths have been uttered by various persons in illustration of all these contrasts.  The philosophy of Voltaire, for instance, is declared to be that of the happy, while Rousseau is the philosopher of the unhappy.  Voltaire steals away their faith from those who doubt, while Rousseau strikes doubt into the mind of the unbeliever.  The gaiety of the one saddens, while the sadness of the other consoles.  If we pass from the marked divergence in tendencies, which is imperfectly hinted at in such sayings as these, to the divergence between them in all the fundamental conditions of intellectual and moral life, then the variation which divided the revolutionary stream into two channels, flowing broadly apart through unlike regions and climates down to the great sea, is intelligible enough.  Voltaire was the arch-representative of all those elements in contemporary thought, its curiosity, irreverence, intrepidity, vivaciousness, rationality, to which, as we have so often had to say, Rousseau’s temperament and his Genevese spirit made him profoundly antipathetic.  Voltaire was the great high priest, robed in the dazzling vestments of poetry and philosophy and history, of that very religion of knowledge and art which Rousseau declared to be the destroyer of the felicity of men.  The glitter has faded away from Voltaire’s philosophic raiment since those days, and his laurel bough lies a little leafless.  Still this can never make us forget that he was in his day and generation one of the sovereign emancipators, because he awoke one dormant set of energies, just as Rousseau presently came to awake another set.  Each was a power, not merely by virtue of some singular preeminence of understanding or mysterious unshared insight of his own, but for a far deeper reason.  No partial and one-sided direction can permanently satisfy the manifold aspirations and faculties of the human mind in the great average of common men, and it is the common average of men to whom exceptional thinkers speak, whom they influence, and by whom they are in turn influenced, depressed, or buoyed up, just as a painter or a dramatist is affected.  Voltaire’s mental constitution made him eagerly objective, a seeker of true things, quivering for action, admirably sympathetic with all life and movement, a spirit restlessly traversing the whole world.  Rousseau, far different from this, saw in himself a reflected microcosm of the outer world, and was content to take that instead of the outer world, and as its truest version.  He made his own moods the premisses from which he deduced a system of life for humanity, and so far as humanity has shared his moods or some parts of them, his system was true, and has been accepted.  To him the bustle of the outer world was only a hindrance to that process of self-absorption which was his way of interpreting life.  Accessible only to interests of emotion and sense, he was saved from intellectual sterility, and made eloquent, by the vehemence of his emotion and the fire of his senses.  He was a master example of sensibility, as Voltaire was a master example of clear-eyed penetration.