 Cleanthes—“smiling”—grants that if Philo can prove that mankind is “unhappy or corrupted”, he will have succeeded in doing in religion (DCNR 10.28/74). He thinks he finally has Philo on the ropes. In forcing a sceptic to prove a positive thesis, he must not only succeed at a difficult task, but violates his scepticism in the process. Cleanthes fails to realize that Philo will make his case without needing to prove anything, nor does he realize that he will soon be the one who needs a proof.