What is the source of the allusion in the sentence below?
Duncan's recent behavior made his parents begin to see his friend Kirk as some sort of Svengali.

 - modern history
 - literature
The source of the allusion Svengali is literature.
In George du Maurier's novel Trilby, Svengali is a hypnotist who exerts such power over the central character that she is suddenly able to sing, which she was unable to do before.
The allusion Svengali means a person with an unduly strong influence over someone else.