Thread:Silver-Haired Seireitou/@comment-1875854-20140606014630/@comment-2089817-20140606020440

The names were inspired by a martial arts manga I read, since I couldn't decide upon more suitable terms, so I just went with those. You should think of Sei and Dou as simply being Yin and Yang, just renamed, to fit martial arts specifically. Sei is expansive movement while Dou is receptive movement. In martial arts, the terms "hard" and "soft" are also used to describe these, but Sei and Dou in this case are used in a far more broad sense. I can explain them like this. Dou is about aggressive straightforward motion. That's why the Heaven School, which is solely focused upon Dou, is only offensive martial arts. Sei, on the other hand, is passive motion. Indirect actions to handle an opponent, such as using their force against them or redirecting their force instead of challenging it. This is why Earth School, which is only Sei, is only a defensive art.

Like the elements in the Ba Gua, the other six schools are based upon ratios between Sei and Dou, allowing for more complex styles and unique techniques. The Thunder School, in particular, follows the Thunder trigram of Yin-Yin-Yang, or rather, Sei-Sei-Dou in this case. It is passive closed movements which is influenced by aggressive expansive motion, which is why the Thunder School is about tightening up the body's muscles and allowing the force to explode outwards upon impact with the target.

I hope this explains it.