I'm worried about that, too. I have 2500+ copies now. There are too many books. The house is small and I can't afford a big villa. The pace of buying books has slowed down a lot in recent years, mainly because there is no room at home. The three walls of the two bedrooms in the house have been changed into bookcase walls the year before last, but they are far from enough. The main solution now is to try to replace paper books with kindle e-books. First of all, I am not a supporter of kindle. Amazon's kindle store in China has more than120,000 e-books. And now in the period of commercial enclosure, all kinds of books are very cheap. The reading experience of kindle is very close to my reading habit, and it is easy to carry. At the same time, it supports synchronization of various devices. You can easily synchronize notes, notes and bookmarks during reading to the kindle of other devices, including e-books, mobile phones, PCs, ipad and so on. There is also a built-in dictionary, which is very convenient to read English. In addition to books purchased by Amazon, Amazon also provides 5G cloud hosting to store e-books that users obtain from other sources. There are also many free e-books available for download online. Most books can be found in electronic versions on the Internet, but many books have poor reading experience, such as scanned versions, or messy typesetting or incomplete pages. Generally speaking, if I can buy paid e-books, I will try to buy paid e-books because the quality of payment is relatively guaranteed. I plan to screen out half of the books for sale in the next two or three years and replace them with kindle e-books. Find free e-books, mainly on Sina microdisk, and most books can be found. Baidu Library also has some materials. My current reading solution is to install good reader+ Sina microdisk +kindle+ibooks+Evernote+ Youdao Notes+Baidu Library +dropbox on iPad mini 2+iPhone 5s. I bought a kindle pw2, which is a bit redundant. Mobile phone +ipad mini is enough.