According to Venerable Master Hsuan Hua, after a person loses his human body, his nature will change and his spirit will be divided. For example, the spirit of one human being can be transformed into many kinds of animal, even eighty-four thousand mosquitoes. Because his wisdom is being divided into many bodies, the resulting beings are dull and stubborn. If he wants to regain his human body, he would need to be “transformed and re-smelted” as if in a chemical factory, the process of which probably would take a long time.
Source:
http://www.drbachinese.org/online_reading/dharma_talks/Innocent_Little_Ghosts_b/Innocent_Little_Ghosts_b9.htmWhat do you guys think?