At this precise period Cinq-Mars—­who, had he not been brought into close contact with a more matured and stronger mind than his own, would in all probability have frittered away his vengeance in petty and puerile annoyances which would rather have worried than alarmed the Cardinal—­formed a fast friendship with Francois Auguste de Thou, who had long ceased to conceal his hatred of the minister.  In the study of his father, the celebrated historian, M. de Thou had learned to feel an innate contempt for all constituted authorities, even while he professed to be at once a Catholic, a royalist, and a patriot; but, unlike his father, the young scholar was not satisfied with theories; he required active employment for the extraordinary energies with which he was gifted; and abandoning the literary leisure in which the elder De Thou so much delighted, he became in early manhood commissary of the army of the Cardinal de la Valette during his Italian campaign, and subsequently he was appointed Councillor of State, and principal librarian to the King.  With his peculiar principles, De Thou could not do otherwise than deprecate and detest the overwhelming power of Richelieu; and long ere he crossed the path of Cinq-Mars, he had entered into several cabals against the minister, a fact which had no sooner been ascertained by the Cardinal than he deprived him of his public offices, and thus rendered his animosity more resolute than ever.  It was in this temper of mind that De Thou met the Grand Equerry; nor was it long ere the wild visions of Cinq-Mars’s passion were fashioned into probability by the logical arguments of his new acquaintance; a circumstance of which he no sooner became convinced than he forthwith resolved not to suffer his indignation to vent itself in mere annoyance, but to seek some more noble and enduring vengeance.

Thenceforward the two friends became inseparable; and when De Thou at length hinted that Cinq-Mars would in all probability, from his great favour with the sovereign, become the successor of Richelieu in the event of his dismissal, the Equerry sprang at once from a peevish and mortified boy into a resolute and daring conspirator, and his first care was to secure the co-operation of his kinsman the Duc de Bouillon; who, while auguring favourably of the plot, and pledging himself to strengthen it by his own participation, represented to his young relative the absolute necessity of obtaining the support of Monsieur.

Gaston had withdrawn from the Court after the birth of the two Princes; and although he had, with his usual pusillanimity, continued to preserve an apparently good understanding with the Cardinal, few were deceived into the belief that this ostensible oblivion of the past was genuine.  Monsieur was, when the subject of the new cabal against Richelieu was mooted to him by Cinq-Mars, residing in the Luxembourg (known at that period as the Palais d’Orleans), whither the Grand Equerry was accustomed to repair in disguise,