If you can allow your qi to spread throughout the body, your body will become very sensitive, so that you will immediately detect a mosquito's stinger piercing the skin (this is what is meant by the phrase, "Not the weight of a feather or a bug more").
如果能夠讓氣遍布全身，身體就會變得非常敏銳，連一隻蚊子叮咬上身都會立刻察覺，這就是「一羽不能加，蟲蠅不能落」。