Each unit and each chapter of this book starts with a number of questions 

 that represent, in our experience, the common curiosities and wonderings of 

 young people. These questions focus the interest and attention of the reader 

 and give direction to the discussion. But there is no pretense that these ques- 

 tions are about to be answered; for while they are genuine and relevant 

 enough, they cannot always be answered in the form they take. Many imply 

 assumptions that are at least of doubtful validity; others involve ambiguous 

 terms. Even a question consisting of but a few familiar words may be quite 

 unanswerable. Why is sugar sweet? Or, Why is blood red? The easiest 

 answers to give and to "understand" and to remember are of course the 

 oldest answers — the kind that primitive man could think up and that the 

 race has indeed remembered to this very moment. Since we frequently are 

 not satisfied with such answers, for we believe them to be often not only 

 evasions of the questions but in most cases effective obstacles to further 

 thinking, we have assumed that it is a large part of our task to clarify the 

 very questions for which answers are sought. At the ends of the chapters are 

 questions (sometimes the "same" questions) which we assume now have new 

 meanings, explore new understandings; and, again, there are questions that 

 can be answered only by interpreting meanings. 



Accepting the scientific way of constructing knowledge out of thought 

 and experience, we suggest at the ends of the chapters numerous "explora- 

 tions and projects", through which students may obtain practical experience 

 in organizing material to guide and check their thinking. (These activities 

 are referred to by number in footnotes at the points in the chapters where 

 they are likely to be most helpful.) 



Another characteristic of the scientific method is the analysis of materials 

 and problems into smaller and smaller bits in search of the ultimate atoms. 

 This leads to a rapid expansion of our knowledge; but it often results in 

 forms of thinking that disregard major problems of daily living. We hope to 

 counteract such atomism by making it clear that life is essentially an inte- 

 grative process, one of bringing various elements together into dynamic 

 wholes. We consider it of special importance today to further a common 

 understanding of the role of co-ordination wherever there is "division of 

 labor", in social life as well as in organisms. This need seems to us quite 

 urgent in a time when the great conflicts of the world arise from the efforts 

 of the several self-conscious groups, associations, classes, nations and other 

 fragments of mankind to control for private ends the social and cultural 

 values to which all have contributed and which arise in any case only from 

 social and cultural interactions. 



We have taken special pains with the illustrations and are particularly 

 grateful to the artists, photographers and others, whose co-operation is 

 acknowledged throughout. The drawings are by Bernard Friedman, Hag- 



iv 



