首楞嚴義疏注經 8.466

8.466

即前詐習為因也。因成詐偽，惑正憑虛，託附畜生便成鬼質，即狐狸、猪犬有異靈者，其類非一，故云遇畜成形。魅即現美形以惑人也。

This is caused by the previously mentioned habit of deceit. Because deceit and falsehood were practiced, deluding what is upright and relying on the insubstantial, attaching to an animal results in a ghost's embodiment. These are the foxes, pigs, and dogs that possess anomalous spirits; their kinds are not one, which is why it says, 'upon encountering an animal, taking shape.' A charmer ghost (mei) is one that manifests an attractive form to bewitch people.