Fair Use
In response to another comment
The Kama Sutra, Tao Tantra, Perfumed Garden, Ananga Ranga,
and so on are not legally covered under copyright laws.
They were written thousands of years before copyright
laws existed. I have checked with three copyright lawyers
and two college departments to confirm this.
Fair use allows the copying of up to 250 words without needing
permission from virtually any published work. When
quoting something you must do it 100% accurately and are
not allowed to do it in an incriminating way. You may use
it for the purposes of backing up your own ideas.