Mencius - Book 4, Part 1, Chapter 2A

Mencius said, 'The compass and square produce perfect circles and squares. By the sages, the human relations are perfectly exhibited.

'He who as a sovereign would perfectly discharge the duties of a sovereign, and he who as a minister would perfectly discharge the duties of a minister, have only to imitate the one Yâo, and the other Shun. He who does not serve his sovereign as Shun served Yâo, does not respect his sovereign; and he who does not rule his people as Yâo ruled his, injures his people.

'Confucius said, "There are but two courses, which can be pursued, that of virtue and its opposite."
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.