Obsidian is a free note-taking application that embodies the principle that your notes belong to you. They live as plain text files in a folder on your own computer, in a format that will still be readable in fifty years, with no account required and no company standing between you and your own writing. What makes Obsidian distinctive is the wikilink: by wrapping any name in double brackets, like [[Tolkien]], you create a link to a note of that name, and the linked note will then know it has been mentioned. If you’ve ever navigated Wikipedia by clicking on the hyperlinks throughout articles, Obsidian empowers you to do that to your own notes.
When I first adopted Obsidian, I encountered the same problem I felt on every digital note taking system. I’d capture something and then have to decide where it goes. Which folder. Which tags. Which category. Often a note belongs in multiple places, and there’s an anxiety in the choosing.
The method I want to describe replaces that decision with a different one. Instead of where does this go? the method I use asks what is this? Instead of making a judgment about how something ought to be categorized, you recognize what it actually is.
Ontology is the study of what exists and how the things that exist relate to one another.
So I call this method the Ontological Type System, after its central commitment: that the notes in your vault should represent things that exist, organized by what they actually are. This provides two advantages. The first is that it reduces the cognitive load of organizing your notes. The second is that it trains you to admire the beauty of reality.
What is The Doors of the Sea?
A short book by David Bentley Hart, written in 2005 after the Indian Ocean tsunami, on where God was in it. You don't have a note for it yet. Do you want one, or to talk it through first?
Talk it through. Owen showed it to me today and we argued about theodicy.
Hart refuses the answer that the suffering was part of God's plan; he treats it as something God opposes. Where did you land?
Unconvinced, but I want to read it. Make the notes, and witness the conversation.
The Doors of the Sea is a Work, a book by a Person. Theodicy is an Idea. The conversation goes in today's journal.
The Doors of the Sea
- type
- Work
- subtype
- Book
- creator
- David Bentley Hart
Theodicy
- type
- Idea
The conversation itself goes in the journal, which is its own method: Witness.
The Six Types
Every note in the Ontological Type System has a property called “Type”. I claim that all things in life, at the resolution that matters for our personal experience, fit into six root types.
[[Person]]: any rational creature, living or dead, biblical, historical, contemporary, or personal. Isaac Newton and your mother are both persons.
[[Place]]: a location or institution. Both physical places (Texas, Mount Everest) and organizational entities (Microsoft, the Roman Senate). Institutions have a kind of locatedness; people gather in them, are formed by them, leave them.
[[Work]]: any artifact made by a person or group. Books, songs, films, paintings, software, sermons, essays.
[[Event]]: any time-bound happening. The American Revolution. Your friend’s wedding. A project you worked on.
[[Idea]]: a concept, phenomenon, or instrument. Ethics, Nuclear Fission, the Printing Press.
[[Journal]]: one’s own dated witness of reality. Structurally different from the other five, doing work the others cannot.
These six are an attempt to name the kinds of entities a thoughtful person actually encounters: agents, locales, artifacts, happenings, abstractions, and one’s own dated experience of them. I have tested this list against years of note-making and found that almost everything I want to record fits cleanly into one of the six. The exceptions are rare, and often reveal a delightful truth: by thinking about what the thing is, you know it better.
Why the Set Is Closed
Every note also has a Subtype, though it’s not always used. Subtypes are an open frontier. They become useful for recurring patterns within a type. Philosophically, they group within types. Practically, the templates for Subtypes can carry different sets of properties. For example:
Since [[The Doors of the Sea]] is a [[Work]], it can be subtyped [[Book]], and the Book template carries what a book needs: an author, a year. A sermon I hear is an [[Event]] with subtype [[Sermon]], and its template carries the fields native to a sermon. In practice most notes leave the subtype blank; nearly all of my Person notes have none, and they work fine.
Add subtypes freely; they refine the ontology without changing its shape.
Not everything I mention gets a note. Everything could; the type system has room for it. Which things do is a matter of discernment, and the test is simple: will I link to it again?
Types are closed by design. Most candidates that come to mind on first encounter, like Project or Topic or Goal, fail to name a kind of thing that does not reduce to one of the six. A project is a Work being executed, or an Event extended in time, or an Idea you are pursuing. A topic is a cluster of Ideas. A goal is an Idea you intend to instantiate as an Event. Adding these as types creates overlap, forces categorization decisions, and dilutes the existing types. The whole reason the system works is that “what is this” has a clean answer inside of it.
Journal as Witness
The five entity types describe what is. They are static in the sense that they describe entities, not happenings. A note about The Lord of the Rings tells you what the book is. It does not tell you when you first read it, or who put it in your hands, or what you were thinking about during the weeks you spent inside it.
The journal does this work. The journal is the daily note, indexed by date, where I record what happened today: who I talked to, what I read, what I thought, what I noticed. A journal entry might say:
2026-10-08
Long talk with Owen at Riverside Park. He showed me The Doors of the Sea by David Bentley Hart and we argued about theodicy for an hour. I was unconvinced but want to read the book.
Owen
- type
- Person
That single sentence, with its four wikilinks, weaves Owen, the park, the book, and Hart into the day, and each of their notes now has a backlink to it. How I keep that journal, and what an agent adds to it, is its own method: Witness.
Classical Realism
The reason “what is this” has a clean answer is that the world exists, but our access to it is finite.
Our notes encode, whether we realize it or not, a metaphysics. The categories you choose to organize your notes commit you to claims about what exists and how things relate. Most popular note-taking systems are built on categories that emerge from your own associative habits: a note can be a “thing,” a “topic,” a “project,” or whatever you happen to need at the moment. This is metaphysically slack. It produces vaults that feel personal but that do not, over time, sharpen the keeper’s perception of reality, because they are not pointed at reality in the first place.
The Ontological Type System begins from a different commitment: notes represent things that exist, in the world, independent of our experience. A note about Marie Curie is a note about a real Polish-French scientist who really lived, really discovered radium, really died of what she discovered. A note about your friend Owen is a note about a real person you really know. A note about the concept of Democracy is a note about a real political idea that has been thought and debated by real people over real centuries. The vault is not a map of your mind. It is a partial, finite, humble map of a fragment of reality at the resolution you can attend to.
This is where the practical payoff and the philosophical commitment meet. The reason capture is cheap under this method is not that I designed a clever taxonomy. It is that reality already has a structure, and this system attends to it. The work of categorization has been done by the One who made the categories. You are only beholding those categories.
How it has changed
I first wrote this page in the spring, and the method has changed since, though not its reason. Then, I made most notes by hand and had an AI produce stubs for public figures. Now an agent makes most notes in my vault under my direction, and when it gets something wrong, the correction becomes a rule it follows the next time. Then, I kept long lists of reference notes made in advance; now a note gets made when I need it, and a thing earns its own note only if I will link to it again. And the indexes I once only described now exist: each type has a hub note that gathers everything of its kind. The reason is the same as it was. What changed is how I keep it.
I used to keep AI away from anything personal. I don’t anymore. The agent works in the whole vault now, because what it gives me as a tool for study and thinking is worth more to me than the line I used to hold. I do what I can, with training on my data turned off and the API where I can use it, and I accept that some private things are exposed. That still bothers me.
Why?
While this method makes creating and organizing notes more efficient and accurate, it serves a deeper purpose I want to state more plainly.
The vault is an act of attention to creation. Every note is a small commitment that this person, this place, this idea, this happening is worth knowing carefully. The cumulative effect of years of such commitments is a vault that increasingly mirrors, in its own small way, the order and richness of the world God made. To know creation rightly is one of the lay vocations. The vault is one tool for that vocation.
We become what we practice. The shape of prayer shapes the soul. The shape of the small daily disciplines, repeated for years, shapes a life. By keeping the Ontological Type System over time, I have developed habits of attention that are not strictly required by the software. I notice persons more carefully, because every person I meet is a candidate for a note, and a note demands I know at least their full name, their roles, their context. I notice the places and institutions I move through. I read books with an eye for the entities the book references. I journal each day of my encounters with the world and what it does to me, and capture my formation in doing so.
These habits are the by-product of the method, the way prayer is the by-product of a regular hour kept. They show up after the practice has been kept long enough to form the practitioner. The closed type set is, in this light, a small daily creed, recited not in words but in the act of filing. Every Person note rehearses the claim that this individual is a real entity worth knowing. Every Place note rehearses the claim that locations and institutions are real and matter. Every Idea note rehearses the claim that abstractions are real things with histories. The form of the notes becomes the form of the attention.