Can a subject resist Hypnotism?

Yesterday, we talked about the "great secret" of hypnotizing someone - they hypnotize themselves. So does that mean you cannot induce someone against their will?

Here is Cardinal Point 5 from Ralph Slater's book:

5. No one can be hypnotised against his will. The complete co-operation of the subject is needed. In some cases, even where the subject tries to co-operate consciously, there may be a subconscious resistance which the subject does not realise. As the hypnotist becomes more successful, he will learn more completely to relax his subjects and induce hypnosis.

Click here for more info on Ralph Slater's classic book on hypnotism.