X PREFACE 



J. B. Conant, whom I was once fortunate enough to serve as teaching 

 assistant, my first introduction to some of the problems here dis- 

 cussed, as well as many pointers along the lines here developed. 

 With T. S. Kuhn I long enjoyed an active teaching collaboration and, 

 though we seem to have arrived at rather different conclusions, many 

 of my themes were first suggested by hard-fought discussions with 

 him. The entire manuscript has been read by JoeJ Cohen, Robert S. 

 Cohen, Wendy Doniger, Gerald Holton, Thomas S. Kuhn, Ernest 

 Nagel, Peter Urnes, and Eleanor Webster— to each of whom I am in- 

 debted for an extended commentary that has furnished a wealth of 

 valuable suggestions. In matters of detail I have had many helpful 

 criticisms from K. D. Clouser, Susan and Stanley Goldberg, James 

 Haber, F. L. Holmes, Stephanie Pfaff, and Michael Simon. My wife 

 has devoted long hours to helping me with the reading of proofs. The 

 skill and patience of Ronald Q. Lewton, who edited this book, have 

 been a strong support in times of need. The unstinted assistance of 

 the foregoing persons has saved me from many serious errors; any 

 that remain are the indivisible responsibility of the author. 



Leonard K. Nash 



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