Darwin’s “big if”, however, is a cautious reminder that he was keenly aware of the lack of evidence for this possibility. The now famous letter was mailed to Hooker on February 1st, 1871, «Down, Selleck BIBW2992 Beckenham, Kent, S.E. My dear Hooker, I return the pamphlets, which I have been very glad to read.—It will be a curious CFTRinh-172 cost discovery if Mr. Lowe’s observation that boiling does not kill certain molds is proved true; but then how on earth is the absence of all living things in Pasteur’s experiments to be accounted

for?—I am always delighted to see a word in favour of Pangenesis, which some day, I believe, will have a resurrection. Mr. Dyer’s paper strikes [?] me as a very able Spencieran production. It is often said that all the conditions for the first production of a living organism are now present, which could ever have been present. But if (and oh what a big if) we could conceive in some warm little pond with all sorts of ammonia and phosphoric salts,—light, heat, electricity &c. present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present day such matter wd be instantly devoured, or absorbed, which would not have been the case

Idasanutlin before living creatures were formed. Henrietta makes hardly any progress, and God knows when she will be well. I enjoyed much the visit of you four gentlemen, i.e., after the Saturday night, when I thought I was quite done for. Yours affecty C. Darwin» His son Francis Darwin included part of this now famous letter as a footnote in the 3rd volume of Life and Letters (Darwin 1887, Cepharanthine Vol 3:168–169). In 1969 Melvin Calvin included the letter (both the transcription and the facsimile) in his book on chemical evolution (Calvin 1969),

calling it to the attention of the origins-of-life community. Darwin’s letter summarizes in a nutshell his ideas on the emergence of life, and provides insights on the views on the chemical nature of the basic biological processes that were becoming prevalent in scientific circles. Although Friedrich Miescher had discovered nucleic acids (he called them nuclein) in 1869 (Dahm 2005), the deciphering of their central role in genetic processes would remain unknown for almost another century. In contrast, the roles played by proteins in manifold biological processes had been established. Equally significant, by the time Darwin wrote his letter major advances had been made in the understanding of the material basis of life, which for a long time had been considered to be fundamentally different from inorganic compounds. Although in 1827 Jöns Jacob Berzelius, probably the most influential chemist of his day, had written that “art cannot combine the elements of inorganic matter in the manner of living nature”, 1 year later his friend and former student Friedrich Wöhler demonstrated that urea could be formed in high yield by heating ammonium cyanate “without the need of an animal kidney”.