The Collected Works of Descartes, Volume 1: Correspondence

Descartes’s letters in a second edition of the Foundations of Medicine original: "Fundamenta Medicinae" in 1644. That same year, a physician from Dordrecht named Beverwick requested these same two responses from the philosopher, and Descartes sent him the drafts original: "minutes"; the preliminary versions or personal copies kept by the author he had kept: they appeared in Beverwick's (Beverovicius) Epistolary Questions original: "Quaestiones epistolicae", a small duodecimo original: "in-12"; a book size where each sheet of paper is folded to create twelve leaves, resulting in a small, pocket-sized book printed in Rotterdam in 1644. Clerselier would only make use of this last work, in which the two letters are incomplete and lack dates.

In 1653, Pierre Borel, "Physician to the King," published in his Summary of the Life of René Descartes original: "Compendium vitae Renati Cartesii" (a small duodecimo of only 55 pages, printed in Castres), a Latin translation of several letters or fragments of letters (eleven items in total) that were then circulating in copy form. These included, among others, two letters to Princess Elisabeth dated May 7 and June 28, 1643. Borel nearly always provided the precise date of the pieces he published; however, Clerselier was either unaware of this publication or, at the very least, took no account of it—though he could have used it to date certain pieces of Descartes’s Correspondence.

Finally, in 1656, there appeared in Amsterdam, under the title The Great Descartes’s Spirit Defended by Himself, or the Honorable René Descartes’s Apologetic Complaint original: "Magni Cartesii Manes ab ipsomet defensi, sive N. V. Renati Des-Cartes Querela apologetica", the philosopher’s long defensive letter to the City Council original: "Vroedschap"; the Dutch municipal administrative body of Utrecht. Descartes appears to have written this short work himself in both French and Latin. It was the Latin text that was published in Amsterdam in 1656; Clerselier would provide the French text in the third volume of his edition in 1667.

Regarding the materials he had at his disposal, Clerselier himself recounts this in the Preface of his first volume. He possessed Descartes’s manuscripts—which is to say, not the letters actually sent by the philosopher, but the drafts minutes from the French "minutes," referring to the original drafts retained by the sender for their own records that he had preserved for a good number of them. These drafts were found among other papers brought from Holland to Sweden. In the inventory drawn up on February 14, 1650, three days after Descartes’s death—of which a manuscript copy by Clerselier himself is now held at the National Library original: "Bibliothèque Nationale" (fr. 13262),