“The surest way to keep a secret is to make someone think they already know the answer.”
Frank Herbert book Heretics of Dune
Source: Heretics of Dune

Heretics of Dune is a 1984 science fiction novel by Frank Herbert, the fifth in his Dune series of six novels. It was ranked as the #13 hardcover fiction best seller of 1984 by The New York Times.
“The surest way to keep a secret is to make someone think they already know the answer.”
Frank Herbert book Heretics of Dune
Source: Heretics of Dune