Indexes, argues Duncan—paraphrasing Jonathan Swift's Mechanical Operation of the Spirit[note 1]—allow the reader a legitimate means of starting a book from the back, a practice he compares to "travellers entering a palace through the privy".

[5] Steven Moore, for The Washington Post, argues that the title's distinct punctuation ensures that the book immediately stands out from being a "dry account of a small cogwheel in the publishing machine".

[6] Jennifer Szalai, for The New York Times, argues that while the book may sound as if it was a history of information science alone, it touches on far broader, more catholic, themes.

[9] The children's author and mathematician Lewis Carroll, in the index to his Sylvie and Bruno contains an entry for "Sobriety, extreme inconvenience of".

[12] Douglas comments that Oldmixon's commission gave him the opportunity for mischief: "As Duncan shows, his index undercuts Echard's intended meanings with sarcastic and deliberate misrepresentations, rewriting history from the safety of the back pages".

Likewise, they are almost always arranged chronologically, which, Duncan says, shifts the quality of what the prose says to a formulaic entry alongside so many others; it is, the author puts it, a "great leveller".

While basic facts were indexable, notes Duncan, problems arose for Pope when he attempted to organise the characters' "manners, passions and their external effects".

[8] This stemmed from the growing necessity of medieval preachers to organise their work coherently, particularly with making quotations and scripture easier to find.

Duncan argues that, when monks, for example, re-wrote existing works—as was the norm before the invention of printing—they effectively rendered any previous index useless, as their pagination was almost certainly to be different.

[17] Ralph Jones, writing in the New Humanist describes his surprise to find that "by the 18th century the index was ... subject divisive enough to invite disdain and incite literary bickering",[5] and accusations of encouraging skim-reading.

Conversely, their commitment was also always to a higher plain, an intellectual exercise requiring neutrality for the sake of the reader, who demands repeated and concerted decision-making on their behalf.

[20] Duncan ascribes a degree of the index's initially poor reputation as being down to the fact that it "kill[ed] off experimental curiosity" in the 17th century and has been looked down on since.

[13] Szalai also questions whether a reader "of an intimidatingly big book decide only to skim the simulacrum—the bite-size summary offered by the index—instead of immersing themselves in the real thing?

[20] Szalai wrote how, while she had previous seen the index as a tool, a mundane, functionary item, Duncan brings imagination and discipline to his topic, "elucidating dense, scholarly concepts with a light touch".

[7] Adam Douglas, in the Literary Review, called it a "puckish eulogy" to the topic and "a trove of bookish anecdote" while being "wittily engaging, wide-ranging".

[10] In the Washington Independent Review of Books, Peggy Kurkowski praises Duncan's ability to convey even the most complex themes "with impish insight and erudition", occasionally titillating and overall a "delightful ensemble of history, technology, literary lore, and information science".

[6] Bain's index was also highlighted for praise by the Literary Review,[10] New York Times[7] and, among others, The Washington Post; in the latter, Steven Moore wrote, "As might be expected, the index—created not by the author but by Paula Clarke Bain—is magnificent".

Szalai describes the relationship between the latter and Duncan's book itself "not just as a guide but also as a companion",[7] while the commercial package "spat out"—in many cases, seemingly random—entries for trivial words such as "alas" and "all the letters".