March 17, 1970

Dr. G. Kretm& F. R. S.
Department of Philosophy
Stanford Wniverdty
Stanford, CA 94305

   ;-. `.. ' '      2

Des r Kreisd,

  You are indeed right isa eayiqg that the study of the origin of
life needs a lVlucky breakthrough%  The problem lis, how to dia-
cover one, One porsfbility concerns the behaviour of tRNA (eecret
enclosed paper). lf present day tRNA does Indeed turn out to have
two coniigurationrrr,  0 f the type rwpsirad, then one knight hope to
produce protoia synthesis in the test-tube with oralp trprimftivar~
fRNA molecules (with amino acide ottaqhed) and a sSmple meeeenger
RNA. Another hope Pe there might e&art a (prebiotfc) mineral with
MeraWw catalytic propertfee, II e. it might catalyre a random
RNA synthesis QT even RNA rapllratlioxzc A third poeetbillty, but
harder to explore, is that the first %aqrmes" consisted of a folded
RNA molecule to which a small peptide (e. g, a tripeptide) had sd-
sorbed, the peptide dofag the chemirtry of the catalysts,

  1 have been considering writing p1 populazt book about directed
panspermia, since laymen can grasp the Odea 80 easily.  Howewet.
the last part of the book would foltow the theme of your letter.
Namely, that although the problem 9s aa hirtarfcoal one, most of the
evidence har dfrrappeared, hypotheses which cannot be tested are not
very aatfsfactory, etc. At the present, I am ao involved ia learning
about the nervous system that anything elre haa to take second plorce.

  f read your twca reviews with pleasure, ar always, though Lt is
the general aature of the remark@ which comes through rather than
the precise content.  For this reason the Wittgeratein one wa8 easier
than the Brouer one, You are incurably par$ithetical, but the footnote8
help to reduce this to reasonable proportion.


Dr. G. Krefeel, F. R. S.

-29

March 17, 1978

F. H. C. Crick
Kieckhefer Distinguished
Research Professor