25. But these writers have not denied the possibility of finding thread in the labyrinth; they have recognized the difficulty, but they have surely not turned difficulty into sheer impossibility. As for me, I confess that I cannot agree with those who maintain that a truth can admit of irrefutable objections: for is an _objection_ anything but an argument whose conclusion contradicts our thesis? And is not an irrefutable argument a _demonstration_? And how can one know the certainty of demonstrations except by examining the argument in detail, the form and the matter, in order to see if the form is good, and then if each premiss is either admitted or proved by another argument of like force, until one is able to make do with admitted premisses alone? Now if there is such an objection against our thesis we must say that the falsity of this thesis is demonstrated, and that it is impossible for us to have reasons sufficient to prove it; otherwise two contradictories would be true at once. One must always yield to proofs, whether they be proposed in positive form or advanced in the shape of objections. And it is wrong and fruitless to try to weaken opponents' proofs, under the pretext that they are only objections, since the opponent can play the same game and can reverse the denominations, exalting his arguments by naming them 'proofs' and sinking ours under the blighting title of 'objections'. 26. It is another question whether we are always obliged to examine the objections we may have to face, and to retain some doubt in respect of our own opinion, or what is called _formido oppositi_, until this examination has been made. I would venture to say no, for otherwise one would never attain to certainty and our conclusion would be always provisional. I believe that able geometricians will scarce be troubled by the objections of Joseph Scaliger against Archimedes, or by those of Mr. Hobbes [90] against Euclid; but that is because they have fully understood and are sure of the proofs. Nevertheless it is sometimes well to show oneself ready to examine certain objections. On the one hand it may serve to rescue people from their error, while on the other we ourselves may profit by it; for specious fallacies often contain some useful solution and bring about the removal of considerable difficulties. That is why I have always liked ingenious objections made against my own opinions, and I have never examined them without profit: witness those which M. Bayle formerly made against my System of Pre-established Harmony, not to mention those which M. Arnauld, M. l'Abbe Foucher and Father Lami, O.S.B., made to me on the same subject. But to return to the principal question, I conclude from reasons I have just set forth that when an objection is put forward against some truth, it is always possible to answer it satisfactorily.