The line you underlined five years ago is talking to you
Why your old highlights are letters from a stranger who used to be you
You pull a book off the shelf — one you haven’t opened in years. Inside, lines are underlined. Margin notes scrawled in your own handwriting. You don’t remember any of it.
But you read the lines, and something happens. They were marked by someone who saw the world differently than you do now. Someone with different fears, different reasons for finding that sentence important on that day.
That someone was you.
This is one of the strangest experiences of a long reading life: meeting a version of yourself you no longer are. And it raises a question worth sitting with — what was she trying to tell you?
Joan Didion thought about this for most of her career. In her essay On Keeping a Notebook, she defended the seemingly pointless habit of recording the small details of one’s life — overheard conversations, weather, what someone wore. Why bother? Her answer became one of the most quoted lines in American letters:
“I think we are all well advised to keep on nodding terms with the people we used to be, whether we find them attractive company or not.”
You change. You become someone else, gradually, while pretending to remain yourself. The person who underlined that book five years ago had a different relationship with ambition, with loss, with what was worth wanting. If you can’t find your way back to her, you’ve lost something more important than a memory.
You’ve lost the thread that makes you, you.
Without a record of who you were, you become a weathervane.
Every new event spins you in a new direction. Every loud opinion pulls you off course. The career you wanted last year is forgotten by next week, replaced by the next thing that caught your attention. You believe you are choosing. Mostly, you are reacting.
Identity — the sense that the person waking up tomorrow is the same person who went to sleep tonight — is not given to you. It’s kept. And it’s kept by the small, almost mundane practice of looking back.
Every culture that took the self seriously developed some version of this practice. Marcus Aurelius wrote his Meditations not for us. He wrote them for himself — daily entries meant to be read back, to remind him who he was trying to be when the day’s events tried to make him forget. Montaigne wrote his Essays in part to track his own changing mind, returning years later to add notes in the margins. Thoreau’s journals ran to two million words, most of them never published. Their authors weren’t recording for posterity. They were keeping themselves company across time.
The form barely matters. A journal. A daily log. A notebook of overheard things. A folder of saved passages. A line in a book.
What matters is that something exists outside your head that you can return to — a record you didn’t write for anyone, that survives your own forgetting, that proves you had a center even when the world tried to scatter you.
Without it, you drift. With it, you can recognize yourself.
Most of us already keep some version of this — old journals, photographs, drafts of essays we never sent. But these capture the expressed self. The performed self. The one we composed for our future selves to find.
Highlights are different. Highlights are not composed. They are the trail of small involuntary recognitions — this. this matters. I don’t know why yet. You weren’t writing for anyone. You weren’t even writing.
You were just paying attention.
Which is why, when you read your own old highlights, they hit harder than your old writing. There is no posture in them. They are the most honest record you have of who you used to be.
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The stranger you’ll be in 2030 needs the same thing the stranger you were in 2020 needed from you — proof that she existed, that she paid attention, that she was here.
She will be confused, changed, looking for a thread back to herself. She will not remember why the year you are living through right now felt like it did. She will need someone to have left a record — not the performed kind, not the public kind. Just the honest kind.
She will need you to have marked the page.
The honest thing about reading is that you forget most of it. The kind thing about reading is that the small parts that mattered — the lines that stopped you, the passages that made you put the book down for a minute — can be saved. Not for the world. Not for a noble cause.
Just for the person you become.
Open a book you read years ago. Find a line you underlined. Read it slowly.
She is talking to you. She has been waiting.
Have you ever opened an old book, notebook, or journal and found a line you’d marked — one that suddenly made more sense, or one that no longer did? We’d love to hear about it. Share your story with us in the comments — we read every one.
And if this resonated, forward it to someone who keeps books with their own handwriting in the margins.
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Such a beautiful read❤️
Great read, Kei Watanabe. Thanks.