"The study of this Book is forbidden. It is wise to destroy this copy after the first reading."
Sometimes words are written that seem to reflect multiple intentions. Where this multiplicity of meaning is not intentional, it's just unclear writing. Where such multiplicity of meaning *is* intended, it's artful.
I'm of the camp that believes its meaning is artfully ambiguous - on a genius level. With some, it reads like a true prohibition; with others, it reads as irony. With each group, I think the comment serves its appropriate purpose. Those who would be put off by such an ironic prohibition are certainly not ready for the book; those who press beyond the prohibition with its inherent irony, however, are ready.
My favorite reading of the comment looks at the way the second sentence assumes that you will, of course, read it anyway, despite the prohibition to study it. It strikes me as very like Mark Twain's kind of understated humor: "It is forbidden to study this book. So after you read it *anyway*..."
Just remember that the guy who wrote that comment also published and distributed the book. It wasn't published against his will or anything like that, so... take that comment with a huge grain of irony.