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Darwin Correspondence Project

To Ernst Haeckel   20 January 1873

Down, | Beckenham, Kent.

Jan 20 1873

My dear Häckel

I received yr magnificent work about 10 days ago. I am fairly astonished at the amount of labour which it must have cost you. The beautiful illustrations alone wd require, I shd think, months upon months of hard work. I have read with great interest the parts which you indicated, as well as some others.1

All that I have read is extremely rich in philosophical discussions on many points. I congratulate you heartily on the completion of this great undertaking; & no doubt it will receive full attention from those naturalists (Alas! in this country few in number) who are capable of appreciating it. You are a wonderful man, but now prove yourself a wise man by taking some rest.

your admiring friend | Charles Darwin


CD’s annotated copy of Haeckel’s Die Kalkschwämme (Calcareous sponges; Haeckel 1872a) is in the Darwin Library–CUL (see Marginalia 1: 357–8). Haeckel had recommended passages for CD to read in his letter of 10 December 1872 (Correspondence vol. 20).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 26 vols to date. Cambridge: Cambridge University Press. 1985–.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.


On EH’s Die Kalkschwämme [1872].

Letter details

Letter no.
Charles Robert Darwin
Ernst Philipp August (Ernst) Haeckel
Sent from
Source of text
Ernst-Haeckel-Haus (Bestand A-Abt. 1: 52/29)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8743,” accessed on 13 December 2019,

Also published in The Correspondence of Charles Darwin, vol. 21