- "I suppose you have Sir Robert Kane's Twilight Compendium?"
- ―Gwendolyn Post
The Twilight Compendium was a book on the occult written by Sir Robert Kane. It was the only one of several books cited by Gwendolyn Post that Giles had on hand in his library.
This was probably the source of Giles' information concerning Buffy and Angel's affair and the rise of Twilight.