The Study of the Cannon Fist in Xingyi (形意炮拳學) from The Study of Xing Yi Quan (形意拳學)

形意炮拳學

炮拳者，屬火，是一氣之開合，如炮忽然炸裂，其彈突出，其性最烈，其形最猛。在腹內則屬心，在拳中即為炮。所謂炮拳似炮屬火者是也。其氣和則心中虛靈，其氣乖則心中朦味，其人必愚矣。其拳和則身體舒暢，其拳謬則四體失和矣。學者務深究此拳也。

孫祿堂

"The cannon fist is classified with the element Fire and is the opening and closing of the unified Qi. It is like the sudden explosion of a cannon shooting its shell, its nature is the most vigorous, its shape the most fierce. In the body it belongs to the heart. In boxing it is like an explosion. This is why it is said that the pounding fist is like a cannon and belongs to fire. When its Qi is harmonius, one’s bosom is empty and alert. When its Qi is irregular, one’s bosom is muddled, one will necessarily be deceitful. When the boxing is harmonius, the body is comfortable. When the boxing is erroneous, it makes the four limbs lose their coordination. This fist should be carefully studied by practitioners."

From the book The Study of Xing Yiquan (形意拳學), by Sūn Lùtáng (孫祿堂), based on the translation by Albert Liu and Dan Miller.