the one-volume propædia is the first of three parts of the 15th edition of "encyclopædia britannica", the other two being the 12-volume "micropædia" and the 17-volume "macropædia". the "propædia" is intended as a topical organization of the "britannica's" contents, complementary to the alphabetical organization of the other two parts. introduced in 1974 with the 15th edition, the "propædia" and "micropædia" were intended to replace the index of the 14th edition; however, after widespread criticism, the "britannica" restored the index as a two-volume set in 1985. the core of the "propædia" is its outline of knowledge, which seeks to provide a logical framework for all human knowledge; however, the "propædia" also has several appendices listing the staff members, advisors and contributors to all three parts of the "britannica".