Lists of Most Difficult Books In August of 2012, Publisher's Weekly posted an article listing what are, in the authors' opinions, the most difficult books ever written. Predictably, James Joyce's Finnegans Wake made an appearance, as did German philosophers Martin Heidegger and G.W.F. Hegel. Conspicuously absent, however, was Gravity's Rainbow by Thomas Pynchon. Much of the avant-garde literary canon was also missing, and Hegel's Science of Logic is arguably more difficult than the listed Phenomenology of Spirit. These omissions raise the question of what makes a book difficult to read, and what the criteria should be for making such a judgment. What Types of Books Should Be Included? It is impossible not to notice that the Publisher's Weekly list included works from literature and philosophy, but not from other realms of human knowledge. For many people, a basic biology textbook would be infinitely more difficult to read than any novel, no matter how obscure. Perhaps it makes sense for a list of difficult books to be limited to books intended to be understandable by people in any field of expertise. But what does it mean to really "understand" a book? Finnegans Wake is, to be sure, a difficult (some say impossible) read, but who can claim to really understand it? People make entire academic careers out of studying the work, so it is not too much of a stretch to propose that there is something fundamentally incomprehensible about that book. Therefore, it does not make sense to say that books have to be universally comprehensible in order to make a list of most difficult books. Limiting the Concept of Difficulty If there is no way to narrow down a list of difficult books by genre or academic field, another approach must be taken. Clearly, the authors of the Publisher's Weekly article arbitrarily included only books in literature and philosophy because those are the areas with which they and their readers are most familiar. It would make more sense for lists of difficult books to be limited to only one field. For example, if the philosophy texts were removed, the Publisher's Weekly list could serve as a list of the most difficult novels ever written - although even then its contents would be highly debatable. How to Judge Difficulty Uniformly What are the most difficult books in, for example, anatomy or microbiology? Anyone unfamiliar with those fields would expect to find any such work difficult, so only anatomists and microbiologists, or other experts on literature in those fields, could authoritatively craft a list of difficult works. If they did, what would their criteria be? What should the criteria be for judging the difficulty of any work? Mastery The idea of mastery could be useful for making lists of the hardest books ever written. In philosophy, for example, it might be true that The Phenomenology of Spirit is slow going, but with perseverance and study most people can achieve a reasonable degree of mastery of the work. On the other hand, ancient philosophical texts like Aristotle's Metaphysics still, thousands of years later, engender radically different interpretations and are matters of general confusion even for expert readers. Works like this, which are difficult if not impossible to master, could work better as candidates for the most difficult books in a subject. Although average people might find a college-level biology or computer programming textbook forbiddingly tough, biologists or computer programmers would see those same books as childishly easy to master. There could be other books in those fields, however, that even seasoned professionals would struggle with, having to return again and again in an attempt to get a grasp on their underlying concepts. Those would be the most difficult books in those fields, not because of the vocabulary, writing style, or other textual vagaries, but because the ideas are difficult to master - even for the masters.