The novels A Case of Conscience (1958; the original short story version appeared in 1953) and Doctor Mirabilis (1964), and the two novellas Black Easter, or, Faustus Aleph-Null (1968) and The Day After Judgment (1970; expanded 1971), which can be read together as one novel, form a work which Blish collectively called After Such Knowledge.

He labeled the series a "thematic trilogy" because, while there are no plot connections between the books (they don't even belong to the same genres), they all share Blish's central theme, the dangers of secular knowledge. Doctor Mirabilis, which Blish considered his best work (although it was not a commercial success and is today difficult to find), is a historical novel about Roger Bacon. A work of fiction on the life of such a legendary and demon-haunted figure would seem to lend itself to fantasy, but Blish chose instead to examine the historical Bacon, the inventor of...