Exhaustive Concordance

I've recently discovered this magnificent book, The NIV Exhaustive concordance. This is a cool book. It's helped me out a lot when looking for scripture. Sometimes I can't remember where to find a particular scripture but I can remember a couple particular words. Looking up the Greek words and definitions makes studying so much more real and fun. But I was curious as to why they called it the exhaustive concordance. Now I know it's because when you dig into it......you become exhausted. =)