Two-thirds gone by tomorrow
Ebbinghaus's forgetting curve, the starting point of memory research, was replicated in 2015 (Murre & Dros, PLOS ONE). Faithful to the original design, one participant memorized nonsense syllables with no review; measured by savings on relearning, roughly a third remained a day later, and forgetting was steepest on the first day. A single-subject nonsense-syllable experiment does not transfer to books as an exact number, but the direction of the curve has held for over a century: forgetting is the default, and day one is where the battle is decided.
So when a month later all that remains is that it was a good book, your memory is not to blame; there was simply no device in place to keep anything. Reading notes are that device, and one well-made page of them is worth a full reread.
All a highlight leaves is the feeling of knowing
In 2013 a team led by cognitive psychologist John Dunlosky published a review of ten common study techniques (in Psychological Science in the Public Interest). Highlighting and rereading landed in the low-utility group; self-testing and spaced review landed in the high-utility group.
The danger of highlighting is not that it does nothing, but that it feels like it works. A familiar sentence reads smoothly the second time, and that smoothness masquerades as knowing. Close the book and try to say the idea in your own words, and the illusion collapses instantly. That is why the center of a note must be retrieval, not transcription.
Three parts that keep a book
Three parts are enough, and each does a different job.
- Quote: the original text verbatim, with the page number. Raw material for future writing or talks.
- Own words: close the book and rewrite the passage in your own sentences. This is the retrieval practice from above.
- Application: one line on where and how to try this in your own work or life. This is the part that turns notes into action.
Write as you read, not after
Postpone notes until after the last page and two things collapse: the opening chapters are already days old and unrecoverable, and the homework has grown to the size of a whole book, so it never gets done. A few minutes at the end of each chapter wins on both memory and habit.
If breaking the flow of reading bothers you, there is a compromise: while reading, leave only dog-ears or flags, then at the chapter's end revisit just those marks and turn them into notes. What matters is that the chapter's own-words section is filled before the book closes.
Three questions before page one
Write three questions you want this book to answer, and reading turns into a search. Chapters irrelevant to the questions can be skimmed without guilt, and your hand stops on its own where an answer appears. The point is that finishing the book stops being the goal.
The questions also become the skeleton of the note. Answer each in a paragraph after finishing, and that is your summary of the book. The questions left unanswered become the criteria for choosing the next one.
Getting next month's you to reopen the note
Spaced review being highly effective is also a conclusion of the research above, and it needs no elaborate system. One rule does it: before starting a new book, skim the notes of the previous one. The rule only works if the notes are not scattered across a different place per book, so keep them all in one spot.
If on reopening you find an own-words entry you want to rewrite, the book truly stuck: your understanding has moved. Add the new version below with a date, and the note for one book becomes a record of how your thinking changed.
Frequently asked questions
I export my e-book highlights. Is that not already a note?
Precisely speaking, it is the quote column filled in automatically. Collection happened, retrieval did not, so almost nothing sticks. Pick only the exported highlights that still look important, fill in the own-words and application parts for those, and from that moment it becomes a note.
Do novels need notes too?
A novel is not read to extract usable information, so there is no reason to force the three-part structure onto it. But a few lines on the scene that stayed with you and why make a fine landmark when you return to the book years later. Notes are a tool shaped by what you want from a book, not an obligation.
My notes keep getting too long to sustain.
More than five three-part entries per book is on the heavy side. Sometimes that means the book deserves it, but usually it means the bar for the quote column is too loose. Tighten it to will I actually quote this someday, and melt the rest into single sentences in the own-words column; the note slims down on its own.