Q: Virtue (also is it common?) とはどういう意味ですか?
A: A positive moral quality that a person can have


Q: Virtue と merit と Advantage はどう違いますか?
A: Merit: An aspect of character trait or behavior deserving approval or disapproval

E.g) The job interviewer shortlist interviewees according to their merits.


Q: Virtue は 英語 (アメリカ) で何と言いますか?
A: QAの全文をご確認ください


Q:Virtue and vice here are ② measured with reference only to whether actions ③ descended material income ④ per person or not. この表現は自然ですか?
A: Virtue and vice here are measured on the basis of whether such actions generate material income or not.
Q: Can you explain what "Virtue is its own reward" means? If you could give me some examples, that'll be nice!
A: It means that being a good person and doing good deeds is worth the effort. There is no need for an award or recognition.

One example might be donating to a charity anonymously. The thought that you have done something out of goodwill is enough.

Hope this helps! ^^