Susanna Clarke's Piranesi is a short novel told entirely in the notebooks of a man who lives in an endless house of statues and tides. Most readers come away talking about the House, which is fair, because it is one of the strangest and most beautiful settings in recent fiction. But the thing that stays useful long after you have finished is the notebook itself. Piranesi is a book about a man who keeps a journal, told through that journal, in which the journal turns out to matter more than anything else he owns. If you have ever tried and failed to keep a record of your reading, he is worth studying as a practitioner.
Notice first that he dates his entries by events rather than by calendar. His entries are headed with things like the first day of the fifth month in the year the albatross came to the south-western halls. He has no calendar, so he built one out of what actually happened. This is a better system than it looks. Ask yourself what you read in March and you will probably draw a blank; ask what you read the month you moved flat, or the fortnight you were ill, or the week of the long train journey, and the books come back immediately. Reading attaches itself to circumstances, not to dates. A journal that records the circumstance is recording the hook you will actually use to find the memory later.
Notice second that he keeps an index. This is the least romantic detail in the book and the most important one. He has ten notebooks, and he has built an index of them, so that when he needs to know what he wrote about a particular statue or a particular flood he can find it. Almost every failed reading journal fails here rather than at the writing stage. People write plenty and then never look at any of it, because there is no way in. A pile of undated, untagged entries is not a record, it is a landfill. If you are going to keep one, decide at the start how you will find a thing again, and let that decision shape the format.
Notice third that he writes down what he sees before he understands it. He describes the halls, the tides, the birds, the statues, in careful detail, with no idea what any of it means. The entries are not analysis. They are observation, recorded at the moment of not knowing. This is exactly the kind of note most readers skip, because it feels premature. You want to wait until you have a view. But the note you write at page ninety, when you are confused and slightly annoyed and not yet sure whether the book is going somewhere, is the one you will find most interesting a year later. Conclusions age badly. Confusion, precisely described, does not.
The engine of the novel, and this is worth knowing before you read it, is that he eventually finds entries in his own handwriting that he does not remember writing. The horror is not a monster in a hall. It is a page in his own book, in his own hand, describing a life he cannot recall having. Your reading journal will do a much gentler version of this to you, and it is one of the quiet pleasures of keeping one. Two years on you will read a paragraph you wrote about a novel and not recognise the reader who wrote it. That gap is the actual measurement. It is the only evidence you will ever have that reading changed you.
So write while you are still inside the book. This is the single habit worth taking from Piranesi and the one most people get wrong. The standard approach is to say nothing until the last page and then attempt a verdict, which produces a review rather than a record, and reviews are the least useful thing you can write about your own reading. The entries with any life in them are the ones written mid-book: what you expected to happen, what is irritating you, which character you have decided you distrust, the sentence you had to read twice. None of that survives to the end. By the last page you have absorbed the answers and forgotten you ever had the questions.
Chaptra's reading journal is built for exactly this shape of note, which is why it does not treat an entry as a review. You log against a book as you go: a started entry, progress notes with the page you have reached, a mood, a finished entry, or a stopped-reading entry with the reason. The entries stay attached to the book and in order, so what you get at the end is not a verdict but a run of dated observations, which is a far better description of what reading a book was actually like. It is the same structure Piranesi is using, minus the tides.
Do not summarise the plot. You can look the plot up in thirty seconds for the rest of your life, and nobody has ever reread their own plot summary with pleasure. What cannot be looked up is your side of it: that you read the middle third on a bad week and it did not stand a chance, that you were wrong about a character and can now say exactly where you went wrong, that a description of a room reminded you of your grandmother's house. That is the material only you have. Spend the entry on it.
Keep the entries short. Piranesi's are often only a few lines, and part of why he sustains the practice across ten notebooks is that no single entry is a project. A journal that demands three considered paragraphs per sitting will be abandoned inside a month, and the abandonment will feel like a personal failing rather than what it is, which is a design problem. Two sentences written on the evening you read the chapter are worth more than the thoughtful essay you fully intend to write on Sunday and will not.
Write down the prediction you currently hold. This is a small trick that repays enormously and almost nobody does it. At some point around a third of the way in, most books have made you believe something: that this marriage will not survive, that the narrator is lying, that the argument in chapter two will turn out to be the whole thesis. Note it, with the page number. Half the time you will be right and it will be dull. The other half you will have a precise record of how a good writer moved you off a position without your noticing, which is the most instructive thing a reader can catch themselves doing.
Record the books you set down as carefully as the ones you finish. Piranesi's notebooks contain the traces of a project that was interrupted, and those traces are the most informative pages in the book. Your abandoned reading works the same way. A one-line entry saying you stopped at page sixty because the voice never settled, or because the timing was wrong rather than the book, builds a list over a few years that will tell you more about your taste than any list of favourites. Favourites tell you what you like. Abandonments tell you what you keep mistakenly thinking you like, which is far more useful when you are choosing the next thing.
Read Piranesi for the House, which deserves the attention it gets. But when you are finished, look again at what the man is doing with his pen and his ten notebooks, dating by albatrosses, indexing his own halls, describing statues he does not understand. It is a working reading journal, demonstrated rather than described. Date your entries by what was happening. Build a way to find things. Write while you are still confused. Keep entries short enough to actually write, note your predictions, and record what you abandoned and why. Do that for a year and you will have something no reading list can give you, which is a record of the reader as well as the reading.