1. The Bible
2. a survival guide with a lot of how tos included
3. a medical guide that includes home remedies and a guide to herbs and medicinal plants
4. The complete works of Jane Austen
5. The complete works of William Shakespeare
6. A book that teaches you how to build your own boat - using readily available materials - that will withstand the ocean and its harsh conditions
7. As many of Charles Dickens' novels and short stories as can be found in one volume
8. a book that teaches you how to create a short wave radio or other device by which you may be able to communicate with someone off the island (also using readily available items)
9. Little Women, Little Men and Jo's Boys by Louisa May Alcott in one volume
10. The complete works of Oscar Wilde (He was so witty that you laugh while reading some of his stories - like The Importance of Being Earnest - and you'd need a book that makes you laugh.)
Granted, I don't know if some of my required books are even in existence, but one could hope - if one got stuck on a desert island!