September 18, 2026
You sit down with a fresh notebook and a pen, and almost at once you hit a snag. Part of you wants to write about the day: the awkward exchange in the post office queue, the way the light fell across the kitchen at four o'clock. Another part wants to copy out the sentence from the book on your bedside table that has been rattling round your head for a week. Two instincts, one blank page. This is usually the moment people start wondering whether they want a diary or a commonplace book.
The two get lumped together under the word "journalling", but they do different jobs, and knowing which one you are actually reaching for saves a lot of abandoned notebooks.
What a diary is for
A diary is a record. You write entries in the order they happen, and the date is the index. That is the whole architecture: one day, then the next, then the next.
Its purpose is to hold a life as it passes. It does not need to be profound or well written. Three lines about a difficult Tuesday will do, because the value sits in the sequence rather than in any single entry. Six months of ordinary days will tell you far more about your year than a handful of polished paragraphs ever could.
Diaries are private by default, written for yourself or for a future version of yourself, and that privacy is what makes them useful. You can be petty, uncertain, contradictory or dull, and nobody is marking it. The date at the top carries the burden of structure, so the words underneath are free to be messy.
The trade-off is that a diary is chronological. Finding one specific thing later is hard, and missing days breeds a low-level guilt that has ended more notebooks than any other cause.
What a commonplace book is for
A commonplace book is a collection. It has no daily rhythm. You add to it when you come across something worth keeping: a line from a novel, a phrase overheard on a bus, an argument you want to remember, a recipe, a fact about moths, a sentence from a lecture that changed how you think about something small.
These books have a long history. Readers in the sixteenth and seventeenth centuries kept them as a matter of course, and John Locke published a suggested method for indexing one. The aim was never to record a life but to build a personal library of passages and ideas, arranged so they could be found again.
Because of that, a commonplace book is organised by theme rather than by time. Headings matter more than dates. Some people keep one running book and index it heavily. Others keep separate volumes for separate subjects, which suits anyone gathering material for writing, teaching or study. The point is the gathering itself, and rereading is part of the design rather than an afterthought.
Record versus collection
A diary answers one question. A commonplace book answers another.
Diary: What happened, and what was it like?
Commonplace book: What have I found, and what is worth keeping?
That pair of questions is a useful test when you are standing in a shop with a notebook in each hand. Are you trying to capture your own life as it unfolds, or collect material from outside it? Most people want one more than the other, and admitting which is the quickest way to stop dithering.
How the note-taking styles compare
Diary style
- First person, present or past tense, written quickly and without drafting.
- Fragments are fine. So are unfinished sentences and notes to self.
- Date at the top, even when the entry is two lines long.
- No need to explain context. You are the only reader, and you already know who "she" is.
- Feelings and reactions are part of the record, not noise around it.
Commonplace style
- Copy the passage accurately, then note the source: author, title, roughly where it appeared.
- Add your own response underneath and mark it clearly, so your words never blur into someone else's.
- Give every entry a heading or a tag so it has somewhere to be filed.
- Leave space after each entry. You will want to add to it in a year.
- Keep an index at the back, or number the pages, so the book still works at two hundred pages.
That last point matters more than it sounds. A commonplace book with no findability turns into a pile of lovely sentences you never look at again, which defeats the purpose entirely.
Can one notebook do both?
Yes, and plenty of people work this way. The trick is to give the two jobs separate territory rather than letting them fight over the same space. A few approaches that hold up:
- Split the page. Top half for the day's entry, bottom half for anything collected that day.
- Index everything. Number the pages, keep a keyword index at the back, and let diary entries and quotations sit side by side without confusion.
- Use one notebook per job. A slim dated book for the diary, a sturdier one for the commonplace material. This is the simplest system if you dislike fiddling with layouts.
A hybrid works especially well for a reading journal: the quotation at the top of the page, your reaction underneath, a date in the margin. You get the collection and the record in the same place, and neither one crowds the other out.
Which should you keep?
Work backwards from what you want to be able to do in a year's time. These questions usually settle it:
- Do you want to remember your life, or remember things? The first points to a diary.
- Do you write in steady daily bursts, or in unpredictable fits and starts? Commonplace books forgive gaps; diaries notice them.
- Are you gathering material for something, such as writing, teaching or a talk you have to give? Then a commonplace book earns its keep.
- Do you want to flick back and find one specific thing? Structure and indexing become essential, which is commonplace territory.
- Do you want a place to be unguarded? That is a diary's great strength and worth protecting.
If you genuinely cannot choose, start with the commonplace book. It costs you less per day, and you can begin a diary later and fill in recent days from memory while they are still fresh.
Starting this week without overthinking it
Pick one format and commit to a fortnight. Neither needs an expensive notebook, and neither needs a system you have to maintain like a second job.
If you choose a diary: write three sentences at the same point each day, and make one of them a concrete detail rather than a summary. "Rained all afternoon, the gutter outside the flat is blocked again, spent an hour rereading chapter four" will read far better in five years than "busy day, tired".
If you choose a commonplace book: pick a broad first heading, something like Sentences I want to steal or How people make decisions, and add five entries this week. Record the source every single time, even if it is only a surname and a page number. Future you will be grateful, and slightly smug.
Three habits keep either one alive: keep the book where you actually sit rather than on a shelf, do not save it for special occasions, and reread a few pages once a month. If the format starts to feel like homework, change it. A diary with three entries a week is worth more than one abandoned in February.
And if you end up keeping both, that is not indecision. They were built for different purposes, they ask different questions of you, and they sit very comfortably on the same shelf.
Photo: Pexels / Pixabay
