All practitioners are like this. As long as your practice is higher than the other's, you can feel the inner air of the other's body after releasing consciousness and judge the level of the other's practice. Of course, if the other party's revision is higher than yours, it is not obvious.

If you want to find out what the other party is doing, the one who is being probed will surely feel that someone is probing him.

It's like having an invisible pair of eyes to look at yourself and see yourself from inside to outside. If Guan Yu had just done so, the boy would have found someone staring...