What the film is really saying
I liked this film a lot because for me its about two mutually exclusive forces, power and love.
I think the film is using witchcraft\magic as a metaphor for a negative unconscious, in a person, which is high on power and therefore automatically low on love (true love not enchantment).
Gillian’s witchcraft\unconscious supplies her with power (magic) but stops any emergence of feeling or love - because that’s its polar opposite. This is why in the film witches can’t cry or blush and why Gillian is stuck in a rut. In so doing the negative unconscious has disconnected her from life and stopped her developing as a person. This is why in the film witches were said to be unsuccessful in life.
When Gillian chooses love she not only breaks free of the negative unconscious but transforms it in the process. This is why in the film the primitive african art shop is transformed into an ephemeral undersea grotto – it’s a metaphor for her new more positive unconscious which supports her, not hinders her. She’s no witch (all power) but she’s no saint (all love) either, she really rejects both poles and so becomes a real person who can be herself but also experience the happiness of relating to others. I can’t explain why she loses her dress sense though !!!
Lots of films in the 1950’s had psychological foundations to them because it was the “new science” and I think its to be found all over Bell Book and Candle. The scene where Gillian and Pyewacket enchant Shep, and their eyes align in a pair, is textbook Jung (founder of analytical psychology) and straight out of a Peter Birkhauser painting !