In this edition the missing part of one letter and eighteen entirely new ones are presented. The search for these letters even extended to Japan. Therefore, all new Smith letter discovered since 1977 are included. In addition, wherever errors were suspected or misreadings have come to light in the standing text as a result of advice from reviewers and correspondents, these have been corrected.

This new edition incorporates eighteen entirely new letters that have been discovered since 1977.

'The editors have done their work well. Not only has the new material been unearthed but it has been annotated.' Times Higher Educational Supplement