Gordon R Dickson 
Final Encyclopedia [EPUB ebook] 
The Childe Cycle Book 7

The Final Encyclopedia tells of the events which occur when the human race is split into three splinter cultures: the Friendlies, fanatic in their faith; the truth-seeking Exotics; and the warrior Dorsai. But now humanity is threatened by the power-hungry Others, whose triumph would end all human progress. Hal Mayne is an orphan who was raised by three tutors: an Exotic, a Friendly and a Dorsai. He is the only human capable of uniting humanity against the Others. But only if he is willing to accept the terrible destiny of . . . Saviour of mankind.