What are the world's most dangerous books? My vote goes to dictionaries. My reason isn't that they give you the means to express ideas persuasively, to pretend to a background or education you don't possess, or to understand people and ideas that would otherwise remain mysteries. The most dangerous thing about dictionaries is the way they steal your time.
    You innocently pick up a dictionary to look up a word that's been on the tip of your tongue, but before you find it, your eye is caught by another word that you like the sound of, or that you haven't come cross for a while, or maybe one that you've never seen before. You have to check the definition. Perhaps it isn't what you expect, or there are more meanings than you were aware of. Whatever the reason for this word distracting you from your search, you find another word in the definition that you decide to look up, or perhaps the words on either side of it intrigue you–which language are they derived from? Why are they spelled the way they are? Do they have any synonyms? What is the best context to use them in? You're taken from one word to another on a journey through the alphabet, led down the byways of the English language's idiosyncrasies. Before you know it, half an hour or more has passed, and you've forgotten the word you first wanted to look up.
    Does it matter? It's the business of writers to know a lot about words, after all. Or is meandering through a dictionary simply another excuse to procrastinate instead of getting down to some writing? Would it be safer to use your spellchecker? Possibly, but if you eschew the delights of flicking through your dictionary, you won't learn anywhere near as much.