Marie Kondo’s book, The Life Changing Magic of Tidying Up, is a worldwide phenomenon. It has sold 1.5 million copies in Japan, and 5 million worldwide. But why is this book so popular–and can it really change your life? We read it to find out.

Tidying Up is a short book built around one insight: We have too much stuff. Even worse, most of our stuff goes unused, wasting space and mental energy while providing little to no value to our lives. So, by throwing away stuff we didn’t want anyway, we become much happier.

There, that’s the concept of the whole book. The other 95% of the book is a system explaining how to get rid of stuff you don’t need, how to organize the stuff you do need, and how to deal with clutter, mementos, photographs, etc. While the book is not, well, exciting, it is generally interesting enough to hold your attention long enough to get started. Then, the hard stuff happens.

I had a closet filled with clothes from high school and earlier. I never wore them, but it also felt terrible to just get rid of them. Tidying Up deals with this problem in an interesting way. Kondo encourages you to think of clothing not just as objects, but as something with feelings. She emphasizes that keeping something locked away in a closet is not the proper way to treat your things, and if you don’t need something anymore, you should be thankful for the joy it once provided in your life–and then ruthlessly move on.

And she is ruthless when it comes to cleaning. She emphatically argues against cardinal cleaning sins we have all committed at one time or another–giving objects to siblings to avoid throwing them out, storing your mementos at your parent’s house, stuffing everything in the closet for “someday”. This advice is repeated to death, not only because the book needs to be a certain length, but because most of us really do need to hear it multiple times for it to truly sink in.

The KonMari method, as her teachings are known, is effective. We tried it at home and got rid of, maybe, 30% of my posessions. To be honest, I feel we should have been even more hardcore. In any event, when it was all said and done, it did make a huge impact on our life. Keeping things clean was much easier (fewer things to lay on the table) and I only once (barely) missed an item I threw away. As for the rest, I don’t even remember what I got rid of.

Which, of course, proves her main point. Getting rid of stuff you don’t need will improve your life and you won’t even notice not having all that stuff you threw away. Having read the book and tried it out myself, I’m convinced she’s right.