@Harlock This is Dao-based. Originally, in Tao/Dao Yin and Yang are the source of everything. Yin is literally just darkness. Yang is literally just light. It came to mean other things later on. Then Fire, Water, Air, Earth, Metal, and Wood are what were born from them. Metal exists separately from the soil. Metal is not dirt, right? Wood is also not dirt. It's not rock, either. So they are separate elements. Mana, as in a spiritual energy, may be similar to Qi/Shi/Ki, but it's not the same. I'd say Mana is more closely related to Yin and Yang. But Mana, at least in stories, is extremely diversified. It can be anything the author wants it to be, and the characters can do just about anything with it (within the construct of that particular story). That's not something that can be done with The Tao because it's a real system, with defined, well-known rules, and the author cannot just randomly change those rules. Too many people would call it out if they did.