I love that every idiom can be decoded only by considering the complete combination tree. I love that so many of this idioms are constructed as pairs and pairs of pairs, and architecture that's even algebraically sound (literally, it's the reason computers architectures use octal).

I like how comprehensive the expression is while being so succinct, in regard to what's ideal to be able to learn something:

自由 -> free mind

自在 -> free existence

So it considers you can devote into the task if you can devote both your thoughts and your time. So it acknowledges that you can think of it but might not have the time, and vice-versa. A lot of care on such a simple expression!! Love it