It’s Not Hoarding If It’s Books: Tsundoku, the Antilibrary and the Philosophy of Unread Books

Last updated: November 4, 2026

“It’s not hoarding if it’s books” is a joke, but the clinical line it jokes about is real. The NHS describes hoarding disorder as a condition in which people collect lots of things and find it very difficult to get rid of them, even when it affects their life; in some homes whole rooms become unusable. A shelf of unread philosophy rarely meets that bar. It can, though: the International OCD Foundation lists paper, books and clothing among the possessions people with hoarding disorder typically keep, and estimates serious hoarding problems in at least 1 in 50 people. What it does meet is a word: Japanese has called the unread pile tsundoku since at least 1879, according to Andrew Gerstle, a professor of premodern Japanese texts at the University of London, quoted by BBC Mundo. The essayist and former trader Nassim Nicholas Taleb went further in The Black Swan (2007) and argued that the unread books are the valuable ones.

The meme plays the bookish version of a four-panel film-still format. A young man in a sunny meadow announces: “I bought a Philosophy book.” A young woman, beaming, asks: “Are you gonna read it?” He says nothing and just looks at her. Her smile fades, and she asks again, more quietly: “Are you gonna read it?” Anyone who owns a copy of Being and Time with a bookmark stuck at page 40 knows that silence.

A Japanese Word That Started as a Jab

Long before it became a bookshop hashtag, the Japanese word tsundoku, buying books and letting them pile up unread, was a joke at a bookish man’s expense.

Open Culture explains that the word is written 積ん読 and dates from the Meiji era (1868 to 1912). It fuses tsunde oku, to let something pile up and leave it, with doku, to read. Open Culture tells it as a pun in which oku was swapped for doku; others treat it as a plain contraction, and the sources disagree on the mechanics. Gerstle, citing the writer Mori Senzo in the BBC Mundo report, points to an 1879 text mocking a “tsundoku sensei”, a teacher who owns plenty of books and reads none of them. Gerstle adds that the word carries no stigma in Japan today. That is the arc book people like: an insult for lazy scholars turned, over a century or so, into a cheerful self-description. English-language media picked it up in the 2010s, with Open Culture’s 2014 piece among the early ones.

Umberto Eco’s Thirty Thousand Books

The antilibrary is Taleb’s name for the unread part of a personal library, and he built the idea around Umberto Eco.

The opening section of The Black Swan is titled “Umberto Eco’s antilibrary, or how we seek validation”, as the book’s table of contents shows. Taleb describes Eco, the Italian semiotician and author of The Name of the Rose, as the owner of a personal library containing thirty thousand books, and sorts its visitors into two groups. The large majority ask how many of these books Eco has read. A small minority understand that a private library is not an ego-boosting appendage but a research tool. From there Taleb draws the line book hoarders like to quote: “Read books are far less valuable than unread ones.” The unread shelves are a map of what you do not know yet, and, in his words, “the more you know, the larger the rows of unread books.”

The Black Swan is a book about how badly we predict rare events, and the antilibrary is his image for intellectual humility: keep your ignorance in plain sight so you stop mistaking what you know for everything there is. Book buyers use it as an alibi, which Taleb’s own description does not support. His antilibrary is a working collection that a reader consults, follows up and grows.

The Arithmetic of the Unread Pile

A rough calculation shows why every serious book lover ends up with a tsundoku pile: a lifetime of steady reading covers perhaps a couple of thousand books, far fewer than most of us will want to read.

Start with reading speed. The psychologist Marc Brysbaert reviewed 190 studies with 17,887 participants and estimated, as the British Psychological Society’s Research Digest reported in 2019, that adults read silently at about 238 words per minute on average. A typical 300-page book runs to roughly 90,000 words, which comes to a little over six hours of reading. Someone who reads half an hour every single day, without exception, gets through about 180 hours a year, or around 29 books of that length. Keep it up for sixty years and the total lands somewhere near 1,700 books.

These are back-of-the-envelope figures, and real lives are messier: holidays add books, small children subtract them, and philosophy is slower going than thrillers. But the scale is the point. Umberto Eco’s thirty thousand volumes would take, at that pace, more than seventeen reading lifetimes. Even a modest home library of a few hundred books outruns the years most people actually spend reading. An unread pile is not a sign that you have failed as a reader. It is what a reading life looks like from the inside, once you accept that you will always want more books than you have time for. Taleb’s antilibrary simply asks you to keep that fact in view.

The arithmetic also suggests a better question than “are you gonna read it?” With a budget of perhaps a few dozen books a year, the real choice is not whether to read everything but which books get the scarce hours. That turns the unread pile into a menu rather than a debt. It is fine for most of it to stay closed, as long as the books you do open are the ones you actually wanted, and not simply the ones that happened to be on top.

When Book Collecting Was Diagnosed as a Disease

Bibliomania, the obsessive collecting of books, got its own book in 1809, when the English clergyman Thomas Frognall Dibdin published Bibliomania; or Book-Madness.

The title page of the Project Gutenberg edition promises “the history, symptoms, and cure of this fatal disease”, in an epistle addressed to the collector Richard Heber. Dibdin was half joking and half confessing, since he was himself a book-obsessed bibliographer, and he wrote for a circle of English collectors who bid each other up for first editions and rare printings. Heber was the perfect patient. His library, by contemporary estimates, ran to well over 100,000 volumes spread across several houses in England and on the Continent, and the Antiques Trade Gazette records his axiom that “no gentleman can be without three copies of a book”: one for show, one for use, one for borrowers.

Fiction took the diagnosis darker. Gustave Flaubert was fifteen when he published “Bibliomanie”, a short story printed in the Rouen journal Le Colibri on 12 February 1837, according to the literary magazine Babar. Its hero, Giacomo, is a former monk turned bookseller in Barcelona whose passion for rare books leads him to kill. Babar notes that Flaubert drew on a report in the Gazette des Tribunaux whose accuracy is uncertain. The twist is pure bibliomania: what breaks Giacomo is the news that the book he thought unique exists in another copy. At his trial, the dead seem to trouble him less than the duplicate.

What 160,000 Adults Reveal About the Books in Their Childhood Home

The strongest case for a full shelf is a 2019 study by Joanna Sikora, M. D. R. Evans and Jonathan Kelley, which found that the number of books in a teenager’s home predicts adult literacy, numeracy and digital skills.

The paper, “Scholarly culture: How books in adolescence enhance adult literacy, numeracy and technology skills in 31 societies”, appeared in Social Science Research (volume 77). It uses the OECD’s adult skills survey (PIAAC, 2011 to 2015), in which more than 160,000 adults estimated how many books their family owned when they were 16. The abstract reports that home libraries boost adult skills beyond the effects of parents’ education and the person’s own education and job, with the largest gains when small libraries grow. According to Smithsonian, around 80 books lifted literacy to the average level and the gains levelled off at about 350 books. Alison Flood’s report on the study adds that adults with only lower secondary education who grew up surrounded by books reached literacy levels similar to university graduates who grew up with few. Home libraries averaged 27 books in Turkey, 143 in the UK and 218 in Estonia.

The study has two limits. The survey relies on adults remembering their childhood bookshelves, and the study is observational: the authors treat the book count as a sign of “scholarly culture” in the home, the talk, habits and expectations that come with books, rather than proof that cardboard and paper do the work by being there. Claims that books on a shelf lower stress circulate widely, but we could not find a study behind them. What the research does support is modest and still good news for book people: a house where books are normal tends to raise readers, whether or not every spine gets cracked.

Montaigne’s Tower and Jefferson’s 6,487 Books

Some of the most influential readers in history lived with libraries far larger than they could ever finish, and treated them less as trophies than as company.

Michel de Montaigne retired in 1571 to a round tower on his estate near Bordeaux and wrote his Essays there, in a library on the top floor. According to an exhibition by Cambridge University Library, he was surrounded by some thousand volumes of ancient and modern writers, and he had quotations from his favourite authors carved into the roof beams, so that he could look up from a page and find another one overhead. “There is my seate, that is my throne”, he wrote of the room, in John Florio’s translation. About a hundred of his books are known to survive. The rest we know mostly from the quotations scattered through the Essays, which makes Montaigne the rare case of a library that turned into a book.

He was also a refreshingly relaxed reader. In his essay “Of Books” he admits that when a difficult passage resists him, he does not wrestle with it for long but leaves it and turns to something else, and that he reads for pleasure and for self-knowledge rather than to finish anything. For a man with a thousand volumes and one tower, that is the healthiest attitude to tsundoku on record: the books are there to be dipped into when they are useful, and nobody is keeping score.

Thomas Jefferson’s collection had an even stranger fate. After British troops burned the Capitol and the young Library of Congress during the War of 1812, Jefferson offered his own library as a replacement, and, as the Library of Congress records, Congress bought 6,487 volumes from him in 1815 for $23,950. Jefferson, who promptly started buying books again, explained himself in four words: “I cannot live without books.” A second fire on Christmas Eve 1851 destroyed nearly two-thirds of the volumes he had sold. Nobody thinks Jefferson read every one of them cover to cover. The point of such a library, as Eco’s visitors failed to grasp, was that it was there when the questions came.

Seneca’s Objection: Libraries as Dining-Room Decor

Roughly two thousand years before the meme, the Roman Stoic Seneca complained about men who filled their houses with books and read none of them.

In On Tranquillity of Mind (9.4 to 9.7), in John W. Basore’s translation, Seneca asks what is the use of having countless books whose titles the owner can scarcely read through in a lifetime. He picks a fight with the historian Livy over the library of Alexandria, where forty thousand books burned: Livy had praised it as a monument to royal taste, while Seneca calls it learned luxury, collected “to make a show”. Then he turns on his contemporaries, men who keep bookcases of citrus-wood and ivory and sit “yawning in the midst of so many thousand books”, whose libraries are “a necessary ornament of a great house”. His rule: buy as many books as are enough, none for show. The same advice turns up in his second letter to Lucilius, in Richard Gummere’s translation on stoics.com: since you cannot read all the books you own, “it is enough to possess only as many books as you can read.”

Seneca’s target is display: a library as a status object, chosen by the binding rather than the content. That is precisely the visitor Taleb mocks in Eco’s apartment, the one who thinks a library is a trophy. Seneca also wrote all this as a very rich man: in Tacitus’ Annals (13.42), the accuser Suillius asks how he had amassed “three hundred million sesterces” in four years of imperial favour. That complicates the sermon, as our post on Seneca’s line the whole future lies in uncertainty discusses.

Why We Buy Books We Never Read

Economists have a name for the gap between the reader we imagine when we buy a book and the reader who comes home tired on a Tuesday: projection bias.

In a 2003 paper in the Quarterly Journal of Economics, George Loewenstein, Ted O’Donoghue and Matthew Rabin opened with a sentence every tsundoku owner will recognise: “People exaggerate the degree to which their future tastes will resemble their current tastes.” Their examples include shopping while hungry and buying winter clothes on a cold day, but the logic fits a bookshop perfectly. Standing in front of a shelf, curious and rested, you buy for the version of yourself who has a free weekend and a burning interest in Byzantine theology. That person rarely shows up, and the book waits on the shelf for someone who may never arrive.

There is also the matter of identity. A book on the shelf is a small promise about who you intend to become, which is why buying one can feel almost as satisfying as reading it. That is harmless, and arguably useful, as long as the promise sometimes gets kept. It turns into Seneca’s complaint only when the shelf is all there is: when books are chosen to be seen rather than opened. The practical fix is low-tech. Keep the unread books where you can see them, take one down whenever you finish another, and let a few go when you notice you have bought them for a person you are no longer trying to be.

Borges and the Library That Contains Every Book

The most famous antilibrary in literature is Jorge Luis Borges’s Library of Babel, a library so complete that it becomes useless, and it is the best argument against the fantasy of ever finishing your pile.

Borges wrote the story while working as a minor functionary in a Buenos Aires municipal library, and it was later collected in Ficciones (1944), as the Encyclopedia.com entry on the story notes. The narrator describes a universe made of “an infinite number of hexagonal galleries”, lined with shelves, through which librarians wander in search of meaning. Because the library holds every possible book, it also holds every true account and every false one, every masterpiece and endless volumes of gibberish, with no catalogue to tell them apart. The librarians’ searches are futile, and yet, the narrator insists, “the library will endure.”

Read next to Taleb, the story is a warning about the limits of the antilibrary idea. Unread books are only valuable if somebody chose them, because selection is what turns paper into a map of curiosity. A pile you built yourself, book by book, says something about the questions you care about. A library that contains everything says nothing at all. Borges, who later became director of Argentina’s national library, understood both sides of the bargain better than almost anyone: the joy of being surrounded by books, and the vertigo of knowing you will never get through them. That vertigo is tsundoku, scaled up to infinity. At the size of a nightstand, it is merely a good habit, and one that a curious mind can live with quite happily for decades.

The Line Between a Tsundoku Pile and a Hoarding Problem

Read together, these sources draw a usable line: unread books earn their place when they serve curiosity, and stop earning it when they serve only the owner’s image or crowd out ordinary life.

Taleb and Seneca agree more than the quotes suggest. Both despise the library as a trophy. Taleb thinks unread books keep you humble about how much you do not know, while Seneca thinks too many books scatter your attention (“Everywhere means nowhere,” he writes in the same letter). The difference is one of temperament: the Stoic wants a reader focused on a few authors, while the risk analyst wants a reader who keeps bumping into surprises. A tsundoku pile can be either a reading list or a display, depending on whether you ever take something down from it.

The clinical line is different again, and it is about harm. The problems the NHS links to hoarding disorder include rooms that can no longer be used and disagreements with friends and family over the things collected, which is a long way from a stack of Kierkegaard on the nightstand. If your stack has started to look more like the NHS list than a nightstand pile, the NHS page above explains where to get help. If you want a reading habit with more structure than an impulse purchase, C.M. Black’s article on why you should read primary sources is a good place to start pulling books off the pile.

Seneca’s complaints about wealth and display take on a different edge in our post on why Silicon Valley keeps rediscovering Stoicism.