Why can't Yunmengjiang Qingxin Clock be touched?

Heart-clearing bell is used for warning. Because bells are used for warning, you can't touch them. In the novel "The Father of the Magic Way", the introduction of the Qing Zhong is: it is hollowed out in silver, engraved with nine lotus petals, tied with a string around the waist, and the jade beads fall with lavender tassels, and the bell rings, so wherever the people of Yunmeng Jiang's family go, the bell is ringing constantly, crisp and pleasant, and it is more useful for clearing the heart, so it is named Qing Zhong.