Things forbidden have a secret charm. Tacitus
We are ever striving after what is forbidden, and coveting what is denied us. Ovid
Sinful and forbidden pleasures are like poisoned bread; they may satisfy appetite for the moment, but there is death in them at the end. Tryon Edwards
The more things are forbidden, the more popular they become. Mark Twain
To make our idea of morality centre on forbidden acts is to defile the imagination and to introduce into our judgements of our fellow-men a secret element of gusto. Robert Louis Stevenson