This unfinished Dialogue, Descartes’ biographer Baillet tells us, was intended to form two volumes written in French. A Latin translation appeared in an edition of 1701 published at Amsterdam. Leibniz was known to have ‘a Dialogue in French’ amongst the unpublished papers of Descartes, and this French text was sought for in vain by MM. Adam and Tannery at the Royal Library of Hanover where it was likely to be found. A young student named Jules Sire was, however, fortunate enough to discover, not Leibniz’s original copy but another. Leibniz was in Paris with Tschirnhaus, and he took Tschirnhaus to see Clerselier, who had what remained of Descartes’ papers. Tschirnhaus copied ‘The Search after Truth’ and sent it to Leibniz, and this was the copy discovered by Sire. We do not know whether Clerselier’s copy was incomplete, or Tschirnhaus’ transcription of it, but it does not give more than half of the Latin version of 1701. Leibniz himself added at the end, ‘I have the rest elsewhere.’ MM. Adam and Tannery thus published Tschirnhaus’s copy of the original in French, completing it from the Latin, and this is the edition here used. The date of the work is unknown.

E. S. H.