It is unknown where and when Despagnet was born or where and when he died. Very likely he flourished in the first half of the seventeenth century. We know only that he was president of the Parlement of Bordeaux. His son Étienne, who had the same interests as his father, became a councillor of the same parlement in 1617. Very likely it was the latter whom Christian Huygens mentioned in his letters.
Despagnet acquired a great reputation as a hermetic philosopher and alchemist. Only two of his alchemic works, which are considered classics of their kind, are extant: the Arcanum Hermeticae philosophiae and the Enchiridion physicae restitutae, both published for the first time in Paris in 1623. The Arcanum is also attributed to an unknown author called the Imperial Knight; that attribution was denied in 1664 by Éitienne, who, when asked about this by Borrichius, affirmed that his father was the author. In the Enchiridion, which is an introduction to the Arcanum, nature is regarded as a constant expression of divine will, it being understood that the paradisiacal state is the true nature and its attainment is God’s will for humanity. The Arcanum, a post-Reformation document, illustrates the deepening sense of the spiritual on the part of physical alchemists.
From Fermat’s letter of 22 September 1636 to Roberval, it appears that in 1629 Fermat had visited Despagnet at Bordeaux. Fermat also sent Étienne the original of the second book of his Loca plana restituta, which he finished in 1629. From Fermat’s letter of February 1638 to Mersenne it appears that he had studied the manuscripts of Viète, which were deposited with Étienne Despagnet and were mentioned in the preface of Van Schooten’s edition of Viète’s Opera mathematica (1646). But, according to Fermat, these manuscripts were so antiquated that it was no longer worthwhile to publish them.
An English translation of the Arcanum can be found in W. W. Westcott, Collectanea Hermeticae, I (London, 1893).
The best account of Despagnet’s works and their several editions can be found in Nouvelle biographie univenelle, XV (Paris, 1854), 402–403. Some information can also be found in C. Henry, “Recherches sur les manuscrits de Pierre de Fermat,” in Bullettino di bibliografia e di storia delle scienze matematiche e fisiche, 12 (1879), 535–537; and A. E. Waite, The Secret Tradition in Alchemy (London, 1926), pp. 39, 338, 341.
H. L. L. Busard