Terence Tao at half his age
"This book was written 15 years ago; literally half a lifetime ago, for me. . . . Clearly, my perspective on life and on mathematics is different now than it was when I was 15. I have not been involved in problem-solving competitions for a very long time now, and if I were to write a book now on the subject it would be very different from the one you are reading here. . . . As I wrote this book before my professional mathematics career, many of these insights and experiences were not available to me, and so in many places the exposition has a certain innocence, or even naivety. I have been reluctant to tamper too much with this, as my younger self was almost certainly more attuned to the world of the high-school problem solver than I am now."
--Preface to the second edition, Solving Mathematical Problems: A Personal Perspective, by Terence Tao. Oxford; New York: Oxford University Press, 2006. Mathematics Library QA300 .T326 2006 Link to MNCAT record
(first edition Deakin University Press, Geelong, Vic., Australia: 1992)
As an example of the kind of book Tao is writing now, see the Book Ring post, Fields Authors.