This book is not simply a translation of the book (Ilfilo d'oro) which was published in Italian in 1994. The volume has been substantially abridged, dropping chapter 9, which analyses the behaviour of Italian entrepreneurs, and all the appendices, which dealt with specific technical issues. On top of this, many footnotes have been trimmed or altogether suppressed and the Appendice Statistica (Statistical Appendix) has been reduced from 73 to 22 tables. On the other hand, this version takes into account some recent works, including some unpublished ones. In some cases, the differences are substantial and some outright mistakes have been corrected. The original chapter 4 has been split into two, and the layout of other chapters (e.g. 5 and 7) has been drastically changed to make the exposition clearer. The author hopes that all these changes have improved the outcome.

The book has greatly benefited from the help of several people. First, from the participants to seminars in the Universities of Pisa, Venice, Florence, Madrid (Carlos III), the European University Institute and the Waseda University (Tokyo) and from a long conversation with Y. Kyokawa and F. Makino, P. Solar. F. Cripps, K. Ishii, M. Scardozzi, R. Tolaini and C. Zanier have kindly given me information or copies of their unpublished works.