What a variety of dangers surrounds us! What a number of wrong paths present themselves in the investigation of the sciences! Through how many errors, more perilous than truth itself is useful, must we not pass to arrive at it? The disadvantages we lie under are evident; for falsehood is capable of an infinite variety of combinations; but the truth has only one manner of being. Besides, where is the man who sincerely desires to find it? Or even admitting his good will, by what characteristic marks is he sure of knowing it? Amid the infinite diversity of opinions where is the criterion[2] by which we may certainly judge of it? Again, what is still more difficult, should we even be fortunate enough to discover it, who among us will know how to make right use of it? If our sciences are futile in the objects they propose, they are no less dangerous in the effects they produce. Being the effect of idleness, they generate idleness in their turn; and an irreparable loss of time is the first prejudice which they must necessarily cause to society. To live without doing some good is a great evil as well in the political as in the moral world; and hence every useless citizen should be regarded as a pernicious person. Tell me then, illustrious philosophers, of whom we learn the ratios in which attraction acts in vacuo; and in the revolution of the planets, the relations of spaces traversed in equal times; by whom we are taught what curves have conjugate points, points of inflexion, and cusps; how the soul and body correspond, like two clocks, without actual communication; what planets may be inhabited; and what insects reproduce in an extraordinary manner. Answer me, I say, you from whom we receive all this sublime information, whether we should have been less numerous, worse governed, less formidable, less flourishing, or more perverse, supposing you had taught us none of all these fine things. Reconsider therefore the importance of your productions; and, since the labours of the most enlightened of our learned men and the best of our citizens are of so little utility, tell us what we ought to think of that numerous herd of obscure writers and useless litterateurs, who devour without any return the substance of the State. Useless, do I say? Would God they were! Society would be more peaceful, and morals less corrupt. But these vain and futile declaimers go forth on all sides, armed with their fatal paradoxes, to sap the foundations of our faith, and nullify virtue. They smile contemptuously at such old names as patriotism and religion, and consecrate their talents and philosophy to the destruction; and defamation of all that men hold sacred. Not that they bear any real hatred to virtue or dogma; they are the enemies of public opinion alone; to bring them to the foot of the altar, it would be enough to banish them to a land of atheists. What extravagancies will not the rage of singularity induce men to commit!