It's often interesting to find out the origin of words. Take "svengali", for instance.

The Oxford Dictionary defines it as "a person who exercises a controlling or mesmeric influence on another, especially for a sinister purpose". Sounds eeeeeeeeeeeevil, doesn't it?

And where does such an eeeeeeeeeeeevil word come from? Well, from "Trilby", a 19th century novel by George du Maurier. The title character is transformed into a famous singer by a hypnotist, Svengali.

He would either fawn or bully, and could be grossly impertinent. He had a kind of cynical humour, which was more offensive than amusing [...] And his laughter was always derisive and full of malice. And his egotism and conceit were not to be borne; and then he was both tawdry and dirty in his person...

Oh, and

[He] flashed his bold, black, beady Jew's eyes into hers...

It's often best not to know the origin of words...