Watching Zhang Yuanrang test his talent with the jade crystal had given him a little more insight into the rules of this world.
Yuan Tian and the others had been watching Zhang Yuanrang's results, but Xu Tong was different. His real purpose in asking Yuan Tian to fetch the jade crystal and have someone test Zhang Yuanrang was not to assess his talent, but to observe through his Divine Sense exactly how talent testing worked in this world.
Now that the test was over, although he had no further samples, he had still grasped the basic principle behind the jade crystal's talent test.
It was actually quite simple. The jade crystal was a mineral imbued with the power of laws. Once fashioned into a testing crystal, it would release a gentle stream of spiritual qi when magic power was injected into it. Repelled by the user's magic power, this spiritual qi would enter the body of the person being tested.
Most people being tested were mortals with no cultivation, so once the spiritual qi entered their bodies, nothing controlled it, and it would spontaneously begin wandering through them.
Along the way, it would absorb some of the scattered spiritual qi within their bodies.
Once the tester withdrew their magic power, the spiritual qi would lose the repulsive force driving it and leave the subject's body, returning to the jade crystal.
At that point, the additional spiritual qi would cause the jade crystal to glow.
In other words, what the jade crystal really tested was a person's affinity for the spiritual qi between heaven and earth.
In daily life, people absorbed spiritual qi into their bodies with every breath. Most of it would leave again as they breathed out, but depending on their individual constitutions, some would remain in their bodies.