Ambushed

A person's meridian was connected to one's dantian in their navel area. A dantian revealed itself after one entered the Saint realm, but until then, it was always hidden, shrouded even from a person's own spiritual sense. 

The meridians came out from either side of the dantian, each route separating into 8 different major routes at once.

Each of these routes was the Spiritual roots in one's body.

Alex realized that if he pushed his Qi out from dantian, it would have to go through one of the 7 different routes, which would give an aspect to his Qi.

Going through the Fire Spiritual Root would give him Fire Qi, and going through Water Spiritual root would give him Water Qi.