PREFACE. 



THERE is an old anecdote told of a clergyman who 

 used, after writing his Sunday sermon, to read it through 

 to his cook, feeling sure that if she could understand it 

 his congregation would. 



Having considerable doubts as to whether the parts of 

 this book which refer to the amounts of Carbon, Hydrogen 

 and Nitrogen in foods would be understood, I have read 

 them to many whom I have taken to be fair types of the 

 intelligence of the kind of readers I have had mostly, 

 though not solely in view the well-informed artizans 

 who use public libraries, and their wives to whom they 

 retail what they have read. The result of these various 

 interviews has been that I have received many sugges- 

 tions to put in fuller explanations in one place, to leave 

 them out in another, because " everybody knows it," to 

 mention where Carbon and Hydrogen and Nitrogen can 

 be seen as it is, " no use talking to people about things 

 they cannot see," or not to trouble about chemistry at 

 all, but to tell people how to get cheap fish and explain 

 how to get over little domestic difficulties about fire- 

 places and hobs and frying-pans I had never dreamt of. 



I have realized the beauty of the old Greek fable of 

 the man and his sons and his donkey, far more vividly 

 than I ever did as a schoolboy. Though I find there 

 are still parts which to some are not clear, I fear I must 

 let the book go as it is. 



