Final answer:
Stoicism is a similarity between classical Greek and classical Roman philosophy. It emphasized self-sacrifice, political service, and the rejection of frivolous luxuries.
Step-by-step explanation:
A similarity between classical Greek and classical Roman philosophy is Stoicism. Stoicism was a Greek philosophy that became popular among many aristocratic Romans. It emphasized self-sacrifice, political service, and the rejection of frivolous luxuries, which aligned with Roman values.