Nations have learned at their own cost that the subjection of man to man is a false idea, an erroneous theory, pernicious alike to master and to slave.

And yet such a social system has stood several thousand years, and has been defended by celebrated philosophers; even to-day, under somewhat mitigated forms, sophists of every description uphold and extol it.

But experience is bringing it to an end.
Time, then, is the criterion of societies; thus looked at, history is the demonstration of the errors of humanity by the argument _reductio ad absurdum_.
Now, the criterion sought for by metaphysicians would have the advantage of discriminating at once between the true and the false in every opinion; so that in politics, religion, and morals, for example, the true and the useful being immediately recognized, we should no longer need to await the sorrowful experience of time.

Evidently such a secret would be death to the sophists,--that cursed brood, who, under different names, excite the curiosity of nations, and, owing to the difficulty of separating the truth from the error in their artistically woven theories, lead them into fatal ventures, disturb their peace, and fill them with such extraordinary prejudice.
Up to this day, the criterion of certainty remains a mystery; this is owing to the multitude of criteria that have been successively proposed.
Some have taken for an absolute and definite criterion the testimony of the senses; others intuition; these evidence; those argument.

M.
Lamennais affirms that there is no other criterion than universal reason.