PREFACE 



*If anybody shall reprove me and shall make it 

 apparent unto me that I do err, I will most gladly 

 retract. For it is the truth that I seeke after, by 

 which I am sure that never man was hurt and as 

 sure that he is hurt that continueth in any error 

 or ignorance whatsoever.' 



MARCUS AURELIUS 



This book was conceived largely at the sink, where most modern 

 husbands have to spend so much of their leisure. My deepest 

 thanks are therefore due to my dear wife who shouldered far more 

 than her share of the domestic drudgery in order that I might slip 

 away to jot down my ideas. I would also like to express my grati- 

 tude to my friends and colleagues at home and abroad who have 

 so generously sent me reprints of their publications. In many 

 cases I have not been able to quote these in the bibliographies for 

 reasons of space, but my debt to the work of others in attempting 

 to cover a very wide field in a single volume must be abundantly 

 clear to the reader. 



J. L. C-T. 



April 1957 



