In the first letter (dated Amsterdam, March 28, 1900) Kuyper responds to the proposal of Yves Guyot (1843–1928), editor in chief of Le Siècle. On March 21, 1900 Guyot started a series of articles directed against 1900.03. The eighteenth and final article was published on April 14, 1900. In a letter to Kuyper dated March 15, 1900, Guyot offered to publish 1900.03 together with his critical commentary as pro and contra in a single brochure. Kuyper found none of Guyot’s conditions acceptable, however. Indeed, in his letter Kuyper judges it very questionable whether the single, poorly documented article in Le Siècle, no. 23381 that he has received from Guyot merits a detailed reply. He also points out that the Revue des deux Mondes retains the authorial rights.

The second letter (dated Grand Hotel, 12 Boulevard des Capucines, April 12, 1900) is a reply to Guyot’s repeated inquiry (in a letter dated April 6, 1900) whether Kuyper would agree to the publication of 1900.03 in a brochure in which it would be preceded by Guyot’s reply, consisting of the eighteen articles from Le Siècle. Kuyper writes that since Guyot has apparently taken no notice at all of his first letter, he has no other choice now but to refer him to the publisher of Revue des deux Mondes (which possessed the copyright to his article).

In a brief letter (dated January 13, 1900) to W.J. Leyds (1859–1940), who assisted him with the documentation for 1900.03, Kuyper writes, “I hope that my article will drive Yves Guyot, with his feeble opposition, from the field” (cf. 1930.05, letter no. 317). This obviously did not occur.

Kuyper’s first letter was also printed along with Guyot’s in De Standaard, no. 8616, April 3, 1900. In De Standaard, no. 8670, June 27, 1900, reference is made to another author who had publicly replied to Guyot and conclusively dealt with his critique.