The writer to whom we owe a comparative history of the systems of philosophy, written with thought and impartiality, has felt keenly that skepticism ought to be considered under two relations: as skepticism of criticism and reform, necessary to correct the presumption of the human mind and to destroy its prejudices; as skepticism absolute and determined, which confounds in a common proscription both truth and error.[494] The first, of which Socrates gave the example, and which Bacon and Descartes have revived, is a sort of intellectual remedy that Providence prepares for healing one of the most fatal maladies of the human mind, that kind of presumptuous ignorance which makes one believe that he knows that which he does not know: the second, which is only the excess and abuse of the first, is this same remedy transformed into poison by an aberration of the human reason which transports it beyond the circumstances which invoke its action, and employs it to devour itself and to exhaust in their source all the causes which cooperate in the progress of human understanding.[495] Arcesilaus was the first to introduce it into the Academy by exaggerating the maxims of Socrates, and Pyrrho made a special system of destruction in it, under the name of _Pyrrhonism_. This system, welcomed in Greece, soon infected it with its venom, notwithstanding the vigorous resistance of Zeno the Stoic, whom Providence had raised up to oppose its ravages.[496] Carried to Rome by Carneades, the head of the third academy, it alarmed with its maxims subversive of public morals, Cato the Censor, who confounding it with philosophy conceived for it an implacable hatred.[497] This rigid republican, hearing Carneades speak against justice, denying the existence of virtues, attacking the Divine Providence, and questioning the fundamental verities of religion, held in contempt a science which could bring forth such arguments.[498] He urged the return of the Greek philosophy, so that the Roman youth might not be imbued with its errors; but the evil was done. The destructive germs that Carneades had left, fermented secretly in the heart of the State, developed under the first favourable conditions, increased and produced at last that formidable colossus, which, after taking possession of the public mind, having obscured the most enlightened ideas of good and evil, annihilated religion, and delivered the Republic to disorder, civil wars, and destruction; and raising itself again with the Roman Empire, withering the principles of the life it had received, necessitated the institution of a new cult and thus was exposed to the incursion of foreign errors and the arms of the barbarians. This colossus, victim of its own fury, after having torn and devoured itself was buried beneath the shams that it had heaped up; Ignorance seated upon its _débris_ governed Europe, until Bacon and Descartes came and resuscitating, as much as was