While Zettelkasten practice improves thinking outside the Zettelkasten, we’ll have to lay out a specific problem with the Zettelkasten Method: we can only think in and within our Zettelkasten when it is available. However, we are often somewhere else.

Naturally, the inbox problem and its two faces arise:

1. Quick Capture Problem: How do we capture ideas when we are not in immediate proximity to our Zettelkasten?
2. Inbox Empty Problem: When do we integrate the ideas captured outside of our Zettelkasten?

The most common mistake that I observe is rushing to a techno-workflow solution. Enabling the capture of ideas on the go quickly is no problem at all. With the omnipresent smartphones, we can type or dictate the idea. With a bit of help from automation and AI, we can create a universal bucket for our inbox:

1. What we type will be moved to our universal inbox directly.
2. What we dictate will be translated by a speech-to-text AI and then moved to our universal inbox.
3. If we make a scribble on paper, we make an image with our phone, let AI transcribe it, or move it as it is to our inbox.

The big problem is how to empty the inbox. The natural assumption is to approach this issue the same way as in task management. That is a mistake.

First, the act of emptying the inbox is organisational. It is about filing away the items from the inbox into the correct context. The task “buy book X” would be moved to the area “errands”. It would be assigned to a specific date so we can make sure we actually accomplish this task, and so on. The desired mode, while emptying the inbox, is not to take action but to remain in the meta-cognitive layer of the action’s context: The task we are focusing on is to empty the inbox, not the individual task we evaluate for its proper context.

This is not how we should engage with ideas in our inbox. There is no consistency about what we need to do to move an item out of our inbox:

• Some ideas don’t need any further process, but might be just helpful background information for tasks and projects to be accomplished. Example: You want to buy a new car, and you heard about an uncommon Romanian brand that is both cheap and reliable because its vehicles have few extra features.
• Some ideas are relatively isolated and can be added to an inventory in your Zettelkasten with minimal processing. Example: You are a personal trainer and learned a trick that helps grip the handle during an exercise on the cable-cross machine.
• Some ideas are exciting and engaging. You don’t need to work on the individual note much to get it right, but the new idea sparks many related ideas in your Zettelkasten. To give this idea its due, you’d have to dive deep into your Zettelkasten. Example: You are a fantasy fiction writer and have a simple idea on how to improve the magic system for your world.
• Some ideas are very promising, but it is tough to get them right to write a note in the first place. Example: You are a software engineer having an idea on how to solve a common problem in making sure that the software code is sound; however, you’d have to really work on the idea to translate it into actual code that can be implemented.

You can’t just “empty your inbox” as a task when the inbox contains such a diverse set of items. If you are a fan of David Allan’s task management system “GTD”, you might object to this thinking by saying: You can apply the 2-minute rule and then categorise the ideas as specific tasks or projects.¹

The problem with that reasoning is that you move the problem just one step further away. You’d have to create either a single container for all the ideas that warrant deeper engagement. Therefore, quite some time, energy, and attention are required, or you’d end up creating several containers with varying requirements on your side, e.g., “difficult to process”, “easy to process, very inspiring”, etc. Then you’d have created yet another inbox or multiple inboxes. So, when do you empty these inboxes?

When it comes to thinking about and crafting ideas, you will never be limited by your workflow. It is always time, energy, and attention. Developing ideas and integrating them into our base of knowledge requires all three of these resources. Your Zettelkasten allows you to externalise your work on your ideas, thereby leveraging your time, energy, and attention. However, this won’t make you quicker at processing ideas, but it will allow you to create more output.

The solution is to make time in your schedule, during which you fully commit your energy and attention to processing and exploiting your ideas. If this sounds familiar to Cal Newport’s term Deep Work, you got the idea.

In both communication, such as email, and task management, the goal is to empty the inbox. The communication and task inboxes have one ideal state: Completeness. The reason for that is trust. You want to make sure that you didn’t miss any of your responsibilities. The value of an inbox is that you don’t lose anything, since it’s one place where new stuff arrives. So, there are two mechanisms by which an inbox system creates trust:

1. There is one place, or at least a limited number of places, where everything new comes into your life. If you checked your inboxes, you can trust that you didn’t miss anything.
2. If your inbox is empty, you can trust that you dealt with each item appropriately. You still can fail in later steps. But at least, you didn’t fail on self-organisation.

This thinking doesn’t apply to any inbox for information and knowledge. Your inbox for information like your reading list, read-later apps, and PDF folder follows an entirely different logic.

1. The empty inbox can’t create trust, since a source in your inbox that you did put there consciously doesn’t have a special state compared to the inboxes that are created through the various feeds in our lives, even if we discount social media feeds and newsletters. Just by listening to some podcasts and getting the occasional book recommendation, you will have more in your inbox than you can read, let alone process.
2. There is limited benefit to the organisation of information. Tagging PDFs, creating categories for online articles that you put in your read-later app, and collecting books that you want to read usually result in piles of stuff that you can’t follow through with.²

In communication and task management, we want to handle everything so we can trust that the system has not missed anything. In our information diet, the goal is to filter as much as possible. Let’s assume you want to learn how to live a healthy, fit life. Is it rational to read everything and anything? Obviously not. You want to focus on a few select sources that offer you the highest information quality. This is one of the main benefits of having a personal trainer. The personal trainer filters for both quantity and quality of information. Then he spoon-feeds you what is relevant to you. The reason why we like book recommendations follows the same pattern: Someone confirmed the value of a source of information in the drowning ocean of books. Or, a last example, the recommendation to read as little as possible on social media and as much as possible in books is a way to filter for quality.

As long as you participate in the modern information landscape by browsing the internet, listening to podcasts, reading blogs, and the like, your inbox is flooded with sources. Having material to read is never a bottleneck. Your inbox becomes just another source of abundance, mirroring the problem of information inflation in the modern age. So, treat it like that. The goal is not to read everything on the internet or every book ever written. The same is true for your inbox. Even further, you shouldn’t try to process everything that you ever read. Reading is in itself a valuable practice. At the same time, it is a surveying method on what is worth a second look. But I hope the pattern is clear: Whenever you are confronted with overabundance, don’t apply completeness as a principle but rather the principle of rational exclusion. I don’t think Dwayne “The Rock” Johnson is reading every fan letter or business proposal he gets. He has a system in place that filters his inbox.

From the beginning of the assembly line of creative knowledge creation to the very end, the guiding principle is:

Your time, energy, and attention are the limiting factors. Filter for the highest possible input quality for each action that relies on these resources.

Let’s take a more positive perspective on abundance:

• It is rather positive than negative that we are confronted with too much food instead of having too little. I’d rather learn to manage my diet, instead of constant hunger and starvation.
• It is rather positive than negative that we are confronted with too much information instead of having too little. I’d rather learn how to filter for quality than try to get any information at all.
• It is rather positive than negative that there are more books than I can read. I’d rather find out what I should read next, instead of not having to read anything at all.
• It is rather positive than negative that I can read much more than I can process. I’d rather process the most valuable sources, rather than have nothing to process and go deep with.
• It is rather positive to create many more ideas that I can turn into publishable writing pieces. I’d rather turn the most valuable ideas of mine into writing, instead of not knowing what to write at all.

An empty inbox is ideal for communication and tasks. Inbox abundance is ideal for information and knowledge work.

Capturing Information Doesn’t Address Our Issue

The problem of abundance is why I don’t put any emphasis on an elaborate capturing system. Being able to capture and automatically put whatever you captured somewhere is not addressing any relevant bottleneck in the assembly line of knowledge work. You will create yet another point of overwhelming abundance in your life. The problem we need to address is the scarcity of time, energy, and attention, not of material to go deep.

On the contrary, you will create more inboxes that will fill up and give you anxiety because of the feeling of obligation to deal with them. To deal with more inboxes, like ideas that you have on your dog walks and commutes, while reading on your phone between meetings, and random ideas while watching documentaries in the evening, you have to build the habit of emptying them. That is yet another task to schedule or another step in your weekly system clean-up. Since implementation is the general bottleneck for almost all changes in our lives, we put even more pressure on ourselves to keep up. But as I argued before, there are barely any upsides.

My approach is to treat situations where I once felt the need to capture all my ideas like a normal person: if I listen to a podcast while walking my dog, I just listen to it. I don’t stress over missing anything. This would only hurt the walk. I want to focus on the experience of walking my dog, watching her sniffing around, getting some fresh air and movement while listening to other people talk. If an idea is so captivating that my mind clings to it, I pause the podcast and think it over. If it sticks, when I come home, I create a note in my Zettelkasten. The same is true when I walk and talk with friends. I have a friend who is a Mennonite preacher. We have intense discussions on the nature of faith and how we live it. Why would I damage the intimacy and shared inspiration by interrupting the flow? I’d rather be in the moment and let the magic of a deep conversation do its work.

What’s the verdict then? The inbox problem in knowledge work is fundamentally different from that in communication and task management. While the latter demands completeness and trust through empty inboxes, the former thrives on abundance and rational exclusion. Capturing ideas is trivially easy with modern technology, but processing ideas is constrained by time, energy, and attention. Creating elaborate capture systems only multiplies your inboxes without addressing the actual bottleneck: dedicating focused time to deep engagement with ideas. An empty inbox in knowledge work is neither achievable nor desirable. It’s a misapplied principle from a different domain.

• Don’t obsess over capturing every fleeting thought.
• Schedule regular Deep Work sessions where you fully commit to processing and developing the ideas that naturally stick with you.
• Don’t mess with the quality of your experiences just to capture everything.
• Focus on filtering for quality at every stage rather than on preserving quantity.
• Think about your information diet the same way you think about your food diet: the problem is not scarcity but abundance, and the solution is not to consume everything but to be selective about what you let in.

I hope this perspective helps you reconsider your relationship with inboxes and capturing systems. Rather than adding another tool or workflow to manage, focus on what actually moves the needle: deep, focused engagement with ideas that matter. That’s where the real work happens, and that’s where your Zettelkasten earns its keep.

Christian’s Comment: If you’re affected and read this far, you probably already thought the following: this means to not capture raw things in your Zettelkasten and add an #inbox tag to it. You may never get around to deal with these! I know from experience.**