Previously, I had
this answer.
But I find this one more apt.
"Instead of slavery, Lucifer here means liberation. This follows the ancient radical doctrine of Gnosticism, which saw the physical universe as an oppressive illusion, and Lucifer, the angel who rebelled against God, as the hero attempting to restore imprisoned souls through knowledge. The Greek word "gnosis" means knowledge. The name Lucifer means "Lightbringer". The Devil initiates the last group of seven cards. Though he usually symbolizes oppression, we also can think of him as signifying hidden desires, fears and other darknesses within ourselves If we wish to go to the deepest levels of the Tarot in our own lives, we must face these things and bring them to the light. Neither the Hierophant nor the Devil has any astrological attribution. We can understand both more deeply if we ponder what connection this implies between them.
Divinatory meanings - Struggles with oppression. Illusions. Dark feelings or desires, especially sexual.
Reversed = Liberation. Bringing things to light."
Cards may foretell. But they never show the entire hand.
[ooc: reposted with permission from an old thread with Lucien
here]