While our brain is good at storing ideas, it has other things to worry about such as the random thoughts passing by each day, context switching from one task to another, and generating new ideas.
A lot of the newer thoughts have more chance to be gone in a few hours.
For this, you want to make a dedicated repository.
- [[id:03289346-3154-4fa1-9bfe-70158012fb5a][Store a sketchbook for your narratives]] allowing you to build your initial imagining of creating a world especially for fantasy settings.
If you want to store an idea for an indefinite future (e.g., a project idea, future hobbies) that you cannot surely do now, you can then create a dedicated inbox.
In practice, this is great as a starter point for [[id:3d1c0313-fa3d-4b18-b435-51d3837e3e2c][Fleeting notes]] or a reading list to [[id:66337935-420c-40e6-81a6-f74ab0965ed5][Maintain your own digital library]].
Beware, this [[id:1bdbdcfa-98f9-4d08-a0dc-ad2f1b9b9ec9][Advice shouldn't be taken literally]].
Not all thoughts are worthy of being noted, the same principle how some thoughts are not worthy to stay in your list.
Don't get into the business of unnecessary note-taking of jotting every thoughts as [[id:b62c61f1-ee12-4bd9-b59a-ec6eafe29f38][Unnecessary optimizations cripple progress]].