Full Idea
Panaetius says that whatever is born must perish, and souls are clearly born, as shown by the resemblance of children to their parents in disposition as well as body; also, anything sensible of pain is susceptible to sickness, and hence perishes.
Gist of Idea
Souls are born, since they are sensitive and inherited, so they must perish
Source
report of Panaetius (fragments/reports [c.145 BCE]) by M. Tullius Cicero - Tusculan Disputations I.xxxii
Book Reference
Cicero: 'Tusculan Disputations', ed/tr. King,J.E. [Harvard Loeb 1927], p.93
A Reaction
These seem to be rather good arguments. If we actually observe what someone's soul is like (through character) it seems rooted in a family and culture, and it certainly seems susceptible to disease. An empirical approach.