He uses household appliances as a metaphor: after checking to see that the appliance itself has no problem, it's necessary to test for an unstable power supply or see if the plug is correctly seated.
若以症狀來分類，除了很大一部分穿梭在各科別、症狀廣泛的患者外，若以西醫的精神官能症來界定，則又可細分為：焦慮症、恐慌症、強迫型精神官能症、慮病症、歇斯底里、解離型精神官能症、憂鬱型精神官能症等各式各樣型態，其中以前述心悸、胸悶為主的「恐慌症」最為典型、常見。