The part which this personage acted in the occurrences of which we are about to give a sketch, makes it worth while to repeat the description of him contained in some of the memoirs of the time. His countenance was handsome and intelligent; he was remarkably courteous and obliging, and entered into any benevolent or pious proposal with the same alacrity with which he agreed to commit a crime. He was vindictive, susceptible of love, and jealous to madness. His extravagance was unbounded, and, being unsupported by any regular income, led him into every sort of wickedness. Some years before his death, he assumed an appearance of devotion, and it is said even wrote some tracts on religious subjects. The Marquis de Brinvillier was much addicted to pleasure. St. Croix got into his good graces, and was introduced into his house. At first he was only the husband's friend, but presently he became the wife's lover; and their attachment became mutual. The dissipation of the marquis's life prevented him from observing his wife's conduct, so that the pair carried on a guilty commerce without any suspicion on his part. His affairs became so disordered, that his wife succeeded, on this ground, in obtaining a separation, and after this paid no respect to decency or concealment in her connexion with her paramour. Scandalous, however, as her conduct was, it made no impression on the mind of the marquis, whose apathy induced the marchioness's father, M. d'Aubray, to use his paternal authority. He obtained a _lettre de cachet_ against St. Croix, who was arrested one day when he was in a carriage with the marchioness, and carried to the Bastile, where he remained for a year. Absence, far from abating the marchioness's passion, only inflamed it; and the constraint to which she found it necessary to subject herself in order to prevent a second separation, inflamed it still more. She conducted herself, however, with such apparent propriety, that she regained her father's favour, and even his confidence. St. Croix availed himself of the power which love had given him over his mistress to root out every good principle or feeling from her mind. Under his horrid lessons she became a monster, whose atrocities, we hope and believe, have hardly ever been paralleled. He resolved to take a dreadful revenge on the family of d'Aubray, and at the same time to get his whole property into the possession of the marchioness, that they might spend it together in guilty pleasures.