The Second Brain: the two-layer system
Claude is brilliant, but fresh out of the box it knows nothing about you: it doesn't know your goals, it hasn't read your notes, it doesn't remember what you decided last month. A second brain fixes exactly that: a folder of files — notes, journals, goals, projects — where Claude lives with your full context and stops being a generic chatbot to become a partner that actually knows you.
What you'll get: an understanding of the two-layer system (the General who thinks with you and the Soldiers who execute), what Obsidian really is, and five real cases where this system already earns money and saves hours — before you build it yourself in the next lesson.
Why Claude alone isn't enough
Every new conversation with Claude starts from zero. You, on the other hand, carry years of context: what you've read, what you wrote in your journal, what you promised in your last quarterly review, the projects you have half-finished. The second brain puts all of that into files Claude can read — and suddenly its answers stop being generic and start being yours.
The system has two layers, and the military metaphor keeps them from blurring.
The two layers: the General and the Soldiers
The General — strategy and storage
Answers "WHAT should we do?". Here Claude is a thinking partner, not a doer. It shares context with your whole brain: notes from books, videos and courses (via the Readwise plugin, or Claude reading your Kindle notes), journals, calendar, long-term goals, reviews with weekly, monthly, quarterly and yearly templates, and the projects folder.
Its CLAUDE.md tells Claude who you are, what you're trying to do, its rules, your strengths and weaknesses, and your goals. Two skills live in this layer: new-project (interviews you to create a new project) and weekly-update (interviews you and refreshes the whole system).
The value: clear goals, a real plan, clean thinking, and instant recall of anything in your life.
The Soldiers — projects
Answer "HOW do we do it?" — and then do it. You open Claude + Obsidian inside a single project folder. One project = one folder with the outputs you want, the inputs (ideas and materials), the process (how Claude helps), and the feedback (metrics, comments, thoughts).
Each project has its own CLAUDE.md and its own skills in a 05-skills folder. Keeping skills per-project stops them from blurring into each other — though you can install one globally just by asking Claude.
The value: a focused Claude that doesn't know or care about the rest of your life. Only this project.
Every project breathes through the same cycle:
What Obsidian is (spoiler: nothing intimidating)
Obsidian is just a folder-and-file viewer "on steroids". Neither it nor VS Code is scary: they are different windows onto the same files.
| Window | What it shows | Who it's for |
|---|---|---|
| Mac Finder | Your folder, as-is | Everyone |
| Obsidian | The same folder, with plugins, themes, and Claude inside | Knowledge work: writing, notes |
| VS Code | The same idea as Obsidian | Coders |
Real cases: the system already works
| Case | What it automates | Result |
|---|---|---|
| Signal app | Ideas board in Obsidian (+ Dispatch from the phone) → Claude designs and tests features inside the project → the spec goes to the co-founder's Claude Code to ship → feedback = user metrics | A real web app with paying users in ~2 months, with no prior coding |
| Email-marketing client | Skills generate email ideas from the client's context and short-form content; a draft skill writes it; a sub-agent reviews; the human polishes | ~$2,000/month |
| Main YouTube channel | Idea → validate demand → research competitors → a packaging skill analyzes titles, thumbnails and keywords and outputs title ideas + tags → Claude helps structure the script → the editor's synced vault handles editing → upload with the generated packaging | A full pipeline from idea to published video |
| Daily channel | Dispatch captures ideas in his exact format; a title skill writes 5 title options; AI pulls 10 thumbnail frames from the recording; an upload skill schedules daily | One video published every day |
| Coaching clients | Call-notes template + a timestamps skill that turns a Loom transcript into timestamped session notes | Notes ready to paste into the client's portal |
Try it: a recall question for Layer 1
Once the General holds your journals and reviews, any fact of your life is one question away.
Look across my journals and weekly reviews from the last three months. What did I write about [my morning routine]? Summarize how it changed month by month, what I committed to in my last [monthly review], and anything I said I would stop doing but keep mentioning.
10-minute practice: sketch your system on paper. On top, Layer 1: write down 3 context sources you already have (a journal? Kindle notes? written goals?). Below, Layer 2: list 2-3 real projects of yours and, for one of them, write out its inputs, its process, its outputs, and its feedback. That sheet of paper is the blueprint for what you'll build in the next lesson.