I read this not long ago on another forum, but I thought it was interesting, so I'm going to share it here.
Take the following sentence: No head injury is too small to ignore.
Now, think about what the literal interpretation of that sentence implies... does it imply that we should treat all head injuries, or that we should be ignoring all head injuries?
Most people, including myself, think the above statement says that we should treat all head injuries. But, that is actually not what that statement is telling us to do at all. Re-read it carefully to see if you can see why. I think it is neat how our mind is quick to correct syntactical errors if we have some formulated opinion as to what is the most reasonable interpretation.
Had the sentence been: No head injury is X to Y.
We would interpret it as it is written, since we have no bias. Anyway, I find all of this interesting.
If you still aren't quite seeing the error in the first sentence, take a look at the following sentence.
The man is too tall to drive a Lotus. This says that the man can't drive a Lotus, because he's too tall. This sentence makes sense... a Lotus is a small car, so if you're too tall you probably would have difficulty driving it.
Now, let's replace the with no.
No man is too tall to drive a Lotus. This clearly means that all men are short enough to drive a Lotus, since there does not exist a man that is too tall to drive one.
Finally, let's go back to the original sentence.
No head injury is too small to ignore. This must mean that all head injuries are big enough to ignore, since no head injury is too small to be ignored. It is clear that this sentence is nonsensical; it implies that we prefer to ignore large head injuries over small ones. Additionally, it tells us that all head injuries are of a size that grants them admission into the 'large' category.
Apparently, this nonsensical sentence comes from Alice in Wonderland by Lewis Carroll. I assume that Carrol did this on purpose, after all, he is known for literary nonsense.