In 1714 he took over his father's tax role. He only rose through luck In 1722, Madame de Barbançois, eldest daughter of
Madame de Fontaine, returning from the thermal baths at
Bourbon-l'Archambault, found herself without lodgings whilst passing through Châteauroux. Dupin hosted her in his house immediately, cared for her, showed himself "unwilling to let her pay a single
sou of all her expenses" and accompanied her to Paris. To thank him her mother offered to introduce him to the immensely wealthy financier
Samuel Bernard, lover of Madame de Fontaine, who recognised his abilities and made him
receveur général des finances for
Metz and
Alsace. On 1 October 1726, after another intervention by Bernard and thanks to a loan from him, Dupin gained one of the forty extremely lucrative places of the
fermier général despite being well under the usual for such a post. He was in that post for 36 years. He was sent around the kingdom for fourteen years and for nearly twelve years was on the Comité des caisses, the Ferme's governing body. He showed particular interest for the authorities for tobacco and major salt
gabelles, which led
Diderot and
d'Alembert to ask Dupin to write the "salts" entry in their
Encyclopédie. On 24 December 1728, he became king's secretary at the Grand Collège, which brought him and his two sons into the nobility. One of the most lavish men of his time, he built a huge fortune and acquired prestigious estates. ==Personal life==