6th July, 1964.
Dear Warren,
It is always a pleasure to hear from you.  Thank you for the suggestion about teaching machines, which I have passed on.  I am tempted to reply at length to your ideas about biology and physicists, but I think it had better wait till next February.  However, I note that your 1948 article has the questions ". . . Is a virus a living organism?  What is a gene, and how does the original genetic constitution of a living organism express itself in the developed characteristics of the adult?  Do complex protein molecules "know how" to reduplicate their pattern, and is this an essential clue to the problem of reproduction of living creatures?  A11 these are certainly complex problems . . . ".
It happens that most of these questions can now be answered.  It might be useful to consider how they were answered, and what type of person discovered the answers.
On the practical side I am quite prepared to welcome as a non-resident Fellow a "student of natural history" provided he can communicate with us, and can suggest possible Fellows who can communicate with the present Fellows.  I would not be keen to have a "neo-vitalist"; that is, a man who thinks that the whole is greater than the parts in some manner which it is impossible to comprehend; (that the "whole is greater than the sum of its parts" is true, in the sense normally used, of the benzene molecule).
Looking forward to a heated discussion in February,
Yours ever,
F. H. C. Crick