IF Theory ReaderApril 2, 2011: Version 2. Minor typo and formatting corrections and a new footnote in the French article. This book has its origins in the early parts of this century. As can easily happen with a project like this, it lost its way some years ago. Last year, it was determined that it should finally come out, even though many of the articles were old. The original authors were contacted, and a number of them were happy to see their articles finally in