At various times he was a Benedictine and librarian of Frederic the Great of Prussia.

Together with the Polish Count Tadeusz Grabianka, also influenced by the Christian mysticism of Swedenborg he founded in 1760 the secret society of "Rite hermétique" or Illuminati of Avignon (Not the Bavarian Illuminati).

He took part in the 1763–64 expedition under Louis Antoine de Bougainville that established the Port Saint Louis settlement in the Falkland Islands, and published a two-volume account of his nature exploration of the Falklands and the Brazilian island of Santa Catarina.

In particular, he gave the first description of the Falklands stone runs phenomenon.

In 1780 the oracle "la Sainte Parole" began to advise the Illuminés of Avignon to leave Berlin to establish elsewhere the foundations of a new Sion.