I think that the most important and interesting book I have read this year is one by Marie Kondo, a Japanese consultant on tidiness:
The basic insight that Kondo had is that objects have power. I grew up in a culture where that was a given: we knew never to touch our feet to books, as that would be disrespectful to knowledge. I treat my lacquered Pilot fountain pen (with an image of Mount Fuji) with so much respect that I don't even take it out of my home. This kind of attitude probably feels weird to the western mind, but I think that to anyone from Asia, it is completely natural. I have noticed the difference between the Japanese/Asian mindset towards objects versus those of westerners whenever I went to Iaido practice anywhere in Europe or the US. Europeans and Americans do not hesitate to touch their feet to the sword, or to let it clatter to the ground, or hit a wall, or a pillar. All this would amount to gross disrespect toward the sword in Japan.
But the problem that everyone eventually faces is that objects lead to clutter in one's life.
Kondo offers a solution that feels a lot like an accelerated path to 悟り, enlightenment: just discard everything. More specifically, lay out everything you own on the floor, category by category, and literally touch each object (you can even talk to it) to find out whether it gives you joy. If it does, keep it, otherwise discard it. You just have to make this binary decision repeatedly, and you will solve pretty much all of your clutter problems, because most of the stuff will be discarded. Of course, she provides a lot of specific detail, and really, her insights reveal how deeply one can understand a topic if only one thinks about it hard enough: she's been at it since she was 5.
One of these insights is to do the discarding all at once (not in one day, but just go through everything category by category). Start with easy things like clothing, and then get to more sensitive things like old photographs; the ordering is important because you need to calibrate your sense of "does it give me joy?".
Another great insight is: keep everything vertical, even clothes, and this includes socks (in tight bundles). This prevents you from piling up stuff and forgetting everything that lies in the bottom of the pile. She doesn't mention this but a natural extension is to not have deep layers in a shelf either---you will forget the things that are deep in the back.
Books that you bought meaning to read them, but never did---discard. Just throw all the paper away, except stuff you are legally required to keep (like the last 10 years' tax returns, in Germany).
People store things in such a way that it's easier to retrieve later on, but that's backwards: we should store them in a way that they are easier to store----that's the reason for the cluttering happening in the first place. Every object has to have a place; that is the key to avoiding clutter. And every object has to be parked in its place once used.
I spent the whole of today trying out the principles Kondo spells out, and it was liberating. I discarded huge amounts of paper (articles I had told myself 10 years ago I'd read but never did, rough paper, old notes, all kinds of crap I kept for no good reason). I discarded about 50 or 60 books (I have the disease of buying books the way people buy coffee). I still have more to discard tomorrow. I gave away all the clothes I don't actually wear any more. Kondo releases you from emotional attachment with these words: the clothes you wore have done their duty; and clothes you bought but never wore, their purpose was to teach you that you didn't want to wear them, and they have therefore done their duty too and deserve to be retired. The same goes for unread books: their job was to teach you that you were never going to read them. They have done their job. Discard them.
Kondo promises that after you do this, all at once, your life will change. I can feel that happening.
While I was reading this book, I got the impression I was reading something written by a 60 year old woman (I read it in English, not Japanese, and the translation is the best writing I have ever encountered of a Japanese text---the translator, Cathy Hirano is someone very special). Then I looked Kondo up on the internet, and I was shocked to see a young woman in her thirties. Watch the youtube excerpt yourself in which she explains her philosophy. What strikes me about her is her total control, her calm confidence. This is how Zen monks talk. They have seen deeper into their minds than anyone else can, and it seems that for Kondo the koan was thinking about tidying up.
Everyone should read this book.