2 6 8 D O C U M E N T 2 3 M A Y 1 9 2 0
Leyden Society for Scientific Lectures. Einstein spoke from a raised lectern, a privilege usually
reserved for the rector of the university (see Friedrich Rosen, Deutsche Gesandtschaft [Haag], to
Auswärtiges Amt, 25 May 1920 [GyBPAAA, R 64673]). After the lecture, people could be
introduced to Einstein in the chambers of the University Senate. For a summary of the lecture and a
report on the proceedings of the evening, see Nieuwe Rotterdamsche Courant, 20 May 1920, Evening
Edition.
An abbreviated version of the report on the lecture by Rosen to the German Foreign Office (see
above) appeared in Berliner Tageblatt, 21 June 1920, Evening Edition.
[2]Einstein had been invited to visit Rosen in The Hague (see R. W. Drechsler to Einstein, 11 May
1920, in Calendar). In his reply, he did not specify a date for his visit, and invited Rosen to his lecture
(see Einstein to R. W. Drechsler, after 11 May 1920, in Calendar).
[3]Possibly Docs. 10 and 20.
[4]Einstein was already considering canceling his participation in the planned conference three
days earlier (see Doc. 17).
[5]In its meeting of 27 March 1920, thirteen candidates were proposed for nine vacancies of foreign
membership of the Section of Sciences of the Royal Academy of Sciences in Amsterdam. On 23 April
1920, five rounds of voting took place; Einstein was elected in the first round (Notulenboek van de
Afdeeling Natuurkunde, 27 maart 1920–29 december 1923, NeHR, Archief KNAW, inv. nr. 14). In a
letter of 18 May 1920, the Ministry of Education informed Pieter Zeeman, Secretary of the Section
of Sciences, that the proposed foreign members had been confirmed by Queen Wilhelmina and could
now be notified of their election (Brievenboek van de Afdeeling Natuurkunde, NeHR, Archief
KNAW, inv. nr. 38).
[6]On Wednesdays, Ehrenfest lectured on mathematical physics from 9 to 11 A.M. (see Jaarboek
1920).
[7]In Doc. 17, Einstein considered it better to arrange his visit to Norway by traveling there directly
from Leyden. The invitation had been extended orally by representatives of the Norwegian Students’
Association (see Doc. 6, note 4).
[8]The violin that had been held up at the German-Dutch border (see Doc. 20).
[9]L. Deng (see Doc. 25).
[10]Maja Winteler-Einstein and Paul Winteler. Probably the preceding document.
23. To Max Wertheimer
[Leyden, 21 May
1920][1]
Lieber Wertheimer!
Sie haben vollkommen recht mir Ihrer Warnung, und ich finde es sehr lieb von
Ihnen, dass Sie mich nicht auf den Leim gehen lassen
wollen.[2]
Hier erlebe ich
schöne Tage. Am 31. komme ich wieder nach Berlin. Hoffentlich sehen wir uns
dann bald.
Herzliche Grüsse von Ihrem
A. Einstein.
AKS. [23 375]. The postcard is addressed “Frau Elsa Einstein Haberlandstr. 5. Berlin,” and post-
marked “Le[ide]n [-], 21.[-]20. 8–9V[oormiddag].” The text is appended to a message in Paul Ehren-
fest’s hand.
[1]Year and month are provided by the reference to the anticipated date of return to Berlin and by
the fact that the document is a response to Doc. 16.
[2]Einstein had initially agreed to accept Hans Vaihinger’s invitation to participate in the “Als-Ob”
conference (see Einstein to Hans Vaihinger, 12 April 1920 [Vol. 9, Calendar]). But Wertheimer, as
well as Paul Ehrenfest and Elsa Einstein, had advised Einstein not to attend the conference, so Ein-
stein changed his mind (see Doc. 22).