The most powerful books reach beyond their pages—beyond those few hours in which they’re read—and indelibly transform how serious readers see the world. Few books achieve such transcendent impact, yet given their physical constraints, it’s remarkable that any do. As a medium, books have no direct means of communicating with readers over time. The physical text is stuck on the page, generally read linearly and continuously in a few sittings.
To be transformed by a book, readers must do more than absorb information: they must bathe in the book’s ideas, relate those ideas to experiences in their lives over weeks and months, try on the book’s mental models like a new hat. Unfortunately, readers must drive that process for themselves. Authors can’t easily guide this ongoing sense-making: their words are stuck on pages which have already been read. How might one create a medium which does the job of a book, but which escapes a book’s shackled sense of time? How might one create timeful texts—texts with affordances extending the authored experience over weeks and months, texts which continue the conversation with the reader as they slowly integrate those ideas into their lives?
Each year, hundreds of thousands of students study Molecular Biology of the Cell. The text presents endless facts and figures, but its goal is not simply to transmit reference material. The book aspires to convey a strong sense of how to think like a cell biologist—a way of looking at questions, at phenomena, and at oneself. For example, it contains nuanced discussions of microscopy techniques, but readers can’t meaningfully try on those ways of thinking while they’re reading. Readers must carry this book’s ideas into their daily interactions in the lab, watching for moments which relate to the exercises or which give meaning to the authors’ advice.
This model of change is brittle: the right situation must arise while the book is still fresh in readers’ minds; they must notice the relevance of the situation; they must remember the book’s details; they must reflect on their experience and how it relates to the book’s ideas; and so on.
As we consider alternative approaches, we can find inspiration in the world’s most transformative books. Consider texts like the Bible and the Analects of Confucius. People integrate ideas from those books into their lives over time—but not because authors designed them that way. Those books work because they’re surrounded by rich cultural activity. Weekly sermons and communities of practice keep ideas fresh in readers’ minds and facilitate ongoing connections to lived experiences. This is a powerful approach for powerful texts, requiring extensive investment from readers and organizers. We can’t build cathedrals for every book. Sophisticated readers adopt similar methods to study less exalted texts, but most people lack the necessary skills, drive, and cultural contexts. How might we design texts to more widely enable such practices?
Guided meditation smartphone apps offer a promising design approach. Meditation’s insights unfold slowly. Aspirants are typically advised to practice daily. Over weeks and months, they may begin to experience the world differently. Some concepts in meditation make no sense if you still can’t perceive your breath clearly, so they’re best introduced later. A book on meditation isn’t well-suited to this kind of slow unfurling: much of it may not make sense initially; readers will need to re-read it again and again as their practice progresses. But a guided meditation app’s experience is naturally spread over time. Each day’s session begins and ends with brief instruction. Instructors offer topical prompts throughout the practice. Intermittent repetition can keep old ideas active in students’ minds until they’re ready to engage. Rather than delivering a bound monograph on meditation, instructors can slowly unfurl an idea over hundreds of days. Critically, these apps are a mass medium, just as books are: lessons can be “written” once and redistributed cheaply to huge audiences. Could this approach be applied more generally?
To engage with a book’s ideas over time, readers must remember its details, and that’s already a challenge. One promising solution lies in spaced repetition memory systems, which allow users to retain large quantities of knowledge reliably and efficiently. Like meditation, these systems involve a daily practice: every day, a reader maintains their memory library by reviewing a few dozen lightweight prompts. Each prompt asks a detailed question, like “What types of stimuli does George Miller’s span of absolute judgment describe?” Each day’s session is different because each prompt repeats on its own schedule. When a user remembers or forgets the answer to a prompt, the system expands or contracts that prompt’s repetition interval along an exponential curve. These expanding intervals allow readers to maintain a collection of thousands of prompts while reviewing only a few dozen each day. Practitioners generally complete their review sessions in moments which would otherwise go unused, like when waiting in line.
Despite their efficacy, these systems are not yet widely adopted. One important barrier to adoption is that it’s surprisingly difficult to write good prompts. To explore one potential solution, we created an experimental quantum computing textbook, Quantum Country. It’s written in a “mnemonic medium,” interleaving expert-authored spaced repetition prompts into the reading experience. Our goal was to help readers engage with challenging technical material by supporting their memory. 
As we interviewed readers, though, we noticed that the regular review sessions didn’t just build detailed retention: the ongoing practice also changed readers’ relationship to the material by maintaining their contact with it over time. These people didn’t just read the book once and proceed with their lives. Quantum Country’s review sessions returned readers to its ideas again and again over weeks and months.
Quantum Country’s prompts are designed to help readers remember technical material, but it may be possible to adapt similar mechanisms to support future timeful texts.
Consider The Elements of Style, a classic writing primer by Strunk and White. The authors demonstrate the value of parallel construction with this example from the Bible: “Blessed are the poor in spirit: for theirs is the kingdom of heaven. Blessed are they that mourn: for they shall be comforted. Blessed are the meek: for they shall inherit the earth.” But it’s not enough to read an example. Good writers’ ears become automatically alert to these constructions. They notice opportunities to create parallelisms, and they notice dissonance when similar phrases are presented differently. It takes time to develop this awareness.
What if, a week after learning about parallel construction, a reader’s review session included this prompt?
The following quote has been modified to remove a parallel construction. How might you rewrite it to add parallel construction? How do the two differ in effect?
“My fellow Americans, ask not what your country can do for you. Instead, reflect on what you can contribute to these United States.” (modified from a quote by John F. Kennedy, which would be revealed in its original form once the reader had finished with the prompt)
A week or two later, a similar prompt might appear with a different distorted quote. For example: “You can fool all the people some of the time, and you can mislead many listeners consistently. But you won’t be able to fool everyone reliably.” (adapted from Abraham Lincoln)
Such prompts might seem onerous or strange on their own, but what if most educated people maintained a regular review practice of the kind we’ve described? The example reflection prompt would sit between others on physics, poetry, and whatever else you’d been thinking about. If you found the prompt useful, it would recur in another week; if not, perhaps it would reappear in a few months. A book like The Elements of Style might include dozens or hundreds of prompts like these on various topics, so that you’d see one or two each day over weeks and months as you integrate its ideas into the way you view and practice writing.
In early chapters of Quantum Country, readers see every prompt as they read the text, and the prompts remain the same in the ensuing review sessions. But in the final chapter, we added a new kind of prompt which changes over time in a programmed sequence. Perhaps future timeful texts could unfurl their contents over the course of many sessions, much as we observed that digital meditation lessons do.
Of course, spaced repetition is just one approach for writing timeful texts. What other powerful tools might it be possible to create, making future books into artifacts that transcend their pages, as they slowly help readers shape their lives?