I owe the philosophy expressed in this book and much of
its detail to many teachers, colleagues, and friends, above all
to a distinguished group I have been privileged to be associated
with at the University of Chicago: Frank H. Knight, Henry C.
Simons, Lloyd W. Mints, Aaron Director, Friedrich A. Hayek,
George J. Stigler. I ask their pardon for my failure to acknowl-
edge specifically the many ideas of theirs which they will find
expressed in this book. I have learned so much from them and
what I have learned has become so much a part of my own
thought that I would not know how to select points to footnote.

I dare not try to list the many others to whom I am indebted,
lest I do some an injustice by inadvertently omitting their
names. But I cannot refrain from mentioning my children,
Janet and David, whose willingness to accept nothing on faith
has forced me to express technical matters in simple language
and thereby improved both my understanding of the points
and, hopefully, my exposition. I hasten to add that they too
accept only responsibility, not identity of views.

I have drawn freely from material already published. Chap-
ter i is a revision of material published earlier under the title
used for this book in Felix Morley (ed.), Essays in Individual-
ity ( University of Pennsylvania Press, 1958) and in still a
different form under the same title in The New Individualist
Review, Vol. I, No. 1 ( April, 1961). Chapter vi is a revision of
an article by the same title first published in Robert A. Solo
(ed.), Economics and the Public Interest ( Rutgers University
Press, 1955). Bits and pieces of other chapters have been taken
from various of my articles and books.

The refrain, "But for my wife, this book would not have
been written," has become a commonplace in academic pref-
aces. In this case, it happens to be the literal truth. She pieced
together the scraps of the various lectures, coalesced different
versions, translated lectures into something more closely ap-
proaching written English, and has throughout been the driv-
ing force in getting the book finished. The acknowledgment
on the title page is an understatement.

My secretary, Muriel A. Porter, has been an efficient and de-
pendable resource in time of need, and I am very much in her
debt. She typed most of the manuscript as well as many earlier
drafts of part of it.

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