眼無神, 拳無魂
Eyes with no expression, boxing without spirit
氣發若風行, 氣納吞百川*
Vapours are emitted like the wind, vapours receive, swallowing a hundred rivers
夫內勁寓於無形之中,接於有形之表,而難以言傳**
The inside strength is in the incorporeal, connecting with a corporeal expression, thus very hard to convey in words
Chinese arts differentiate strength from just body force. In Chinese, force is 力, which originally was a representation of human tendons or connective tissues***, "筋也。象人筋之形". Strength is 勁, the "underground river", 巠, of force, 力.