How I turned my Obsidian, which I had abandoned for a year, into an 'automatically growing second brain' in just 3 steps
"My notes keep increasing, but I can never remember where I wrote things down."
"Linking is a hassle, so my notes remain scattered."
"I can't keep up with folder organization or tag management, so I end up abandoning it."
Do you have these kinds of worries?
Hello, Aisuke here.
"Second Brain" - I've been using Obsidian for over a year now, drawn in by that cool-sounding term.
But, to be honest, I wasn't feeling the benefits at all.
Actually, the cause of all three of these problems lies in the same place.
The assumption that humans have to do the organizing.
Once I realized this and changed the system, the time spent linking notes went from 5 minutes to 0 minutes. Folder organization and tag management, which used to take hours and never finish, now run on autopilot (0 minutes).
...Before changing the system, it had become a purple note-taking app. It was truly a case of 'having it but not using it'.
▼ Obsidian Related Articles
The Obsidian plugin that brought about this change is Claudian.
In this post, I'll talk about how to create a 'second brain' that anyone can do, using Claudian to 'turn your accumulated notes into your own personal AI'.
What is Claudian?
Claudian is an integration of Obsidian × Claude Code.
Simply put,
it's something where AI directly accesses your notes, extracts necessary information, analyzes it, and makes suggestions based on the content of your notes.
For those who are a bit more tech-savvy,
it means your entire Vault (Obsidian storage) becomes the 'working directory' for an AI agent (Claude Code).
Main features available in Claudian
1. Direct reference to notes and folders
When you ask a question in the chat, Claudian autonomously explores your Vault to find relevant notes and folders. It searches and reads the necessary files on its own, even without organization or tagging.
2. Specify specific files with @mentions
By typing @ in the chat, you can directly specify particular notes or folders within your Vault.
Analyze @filename
3. Skills are also available
By typing / or $ in the chat, you can call up reusable prompt templates (skills).
In other words, even without linking, folder organization, or tag management, the AI agent autonomously explores your notes to find the information you need. This is the prerequisite feature for realizing a second brain through 'near-automation'.
However, it won't work well with the default settings, so I will explain the detailed method later.
Three use cases you can achieve
Specifically, what can you do using Claudian? I will introduce three examples.
✨ 1. 'Personal Advisor' transformation
By having it learn your note account information (monthly PV, failure logs, study notes), you can create a 'personal advisor' that understands your personality.
'What should I do today?'
Just by asking this, you will receive suggestions based on your strengths, things you have avoided, and recent learnings. This is quite powerful.
✨ 2. 'Decision support'
When you are unsure which of two new projects to choose, if you have Claudian cross-search your past success and failure patterns, your note assets will turn into the 'basis for your decisions'.
✨ 3. 'Review and Application'
Past notes, even if you thought they were important when you wrote them, you tend to forget them as time passes, right?
"Summarize my notes on concentration."
If you give this instruction, it will search and organize relevant notes from your entire Vault and even suggest applications for your recent challenges. Past learning becomes useful again.
How to build your own 'personal AI': The 3-step cycle
It looks difficult, but it's actually simple. Just repeat these 3 steps infinitely.
🔄 STEP A | Accumulate notes
Turn your thoughts, failures, learning, and judgments into notes in any form.
Method 1: Write down whatever comes to mind in Obsidian every day.
Method 2: Copy and paste your chat history with Claudian and save it as a note.
"No special organization required". Don't worry about linking, folder categorization, or tags; just write down what you think in the form you think of it. This is the first step for the super lazy.
🔄 STEP B | Ask questions
Just ask what you want to know from your Claudian chats. No complex instructions are needed.
"What can I learn from this month's failures?"
By just asking this, it will find notes related to "failure" from your entire Vault, read and analyze them, and give you concrete advice based on your note assets.
🔄 STEP C | Accumulate notes again
Write down the suggestions and insights you received from Claudian into new notes. That's all.
STEP A → STEP B → STEP C → As the loop continues, the AI grows into your 'personal advisor.' As your note assets increase, the learning data grows, the accuracy of suggestions improves, and even higher-quality insights are turned into notes—this virtuous cycle is the reason why a second brain is completed through 'near-automation'.
⚠️ Note: Logs are not accumulated automatically by default
This is why I wrote earlier that "it doesn't work with the default settings."
Claudian does not have a setting from the start to "automatically turn chat content into notes and save them." The "accumulate notes again" in STEP C is not magic that happens on its own without doing anything; it is a mechanism that only starts working once you incorporate instructions yourself in the system prompt to "save the main points of the conversation as a note."
This is not a failure story, but a discussion of the premises and specifications of the tool called Claudian. If you introduce it without knowing this, you will be disappointed, thinking, "Oh, it's not as automatic as I thought," so please be aware of this beforehand.
(I will explain the specific way to set up this system prompt in the linked article below.)
Even with the method so far, it's honestly a bit of a hassle, isn't it? By using custom prompts and skills, you can bring this cycle even closer to being 'almost automatic'.
I recommend experiencing the 'basic cycle' first, and then customizing it as needed.
Required Environment and Setup Procedure for Claudian
Honestly, since this content is explained in detail in other people's articles, I will introduce it roughly. Reference article is also included.
Prerequisites (Please make sure you have these)
Claude Code CLI must be installed (Native installation on a local machine is recommended)
Claude subscription/API key or a compatible provider (OpenRouter, Kimi, etc.) must be available
Obsidian v1.7.2 or later (Only supported on macOS, Linux, and Windows desktop versions)
Setup Procedure (3 Steps)
Step 1: Install the Claudian plugin
Open Obsidian settings, click 'Community plugins' -> 'Browse'. Type 'Claudian' in the search bar to install and enable it.
Step 2: Open the chat sidebar
Click the ribbon icon in Obsidian or run the Claudian command from the command palette. This will open the chat sidebar.
If it doesn't start correctly: If you get the error 'Claude CLI not found', please manually specify the 'Claude CLI path' from the Claudian settings screen.
▼ For those who want to know more detailed methods, check out this article ✨
Step 3: Things to try first
Once the chat sidebar is open, let's have it do a simple task first.
'Link notes in the Vault that have high relevance'
Just by giving an instruction like this, Claudian will explore your note assets and perform the work. In this way, your 'cycle' begins.
Summary: The 'Second Brain' unleashed by automation
The reason why the ideal of building a 'second brain' in Obsidian didn't come true for me is simple.
The effort required for organizing and linking was simply too much for most people.
Claudian solves that challenge with near-total automation. As long as you focus solely on 'collecting notes,' AI agents will automatically explore, analyze, and suggest insights from your note assets. This is the new form of a 'second brain' realized by Claudian.
For more, please check out the two links introduced above. Stay tuned.