The Penultimate Truth (Cover) Picture from Philip K. Cover for "The Penultimate Truth". "The Penultimate Truth" is a 1964 science fiction novel by American writer Philip K. Dic-k. It is based on Dic-k's 1953 short story "The Defenders".
Tunnel in the Sky was one of the first Heinlein books I ever read; my dad had an old copy kicking around, and I ended up mooching and reading it some time in my middle teens. This was one of the first books that started my love of golden age sci-fi.