What is the most distinctive feature of human nature? Does human nature play any significant role in explaining ethical objectivity? How do we arrive at moral judgments? What is the relationship between moral judgments and moral motivation? In answering these questions, this book defends a naturalist, realist and internalist theory of the foundations of ethics. This theory, grounded on a particular concept of humanity, combines insights from Mencius and David Hume. The views of each show how important features left underdeveloped by the other can be supplemented and refined. The unified theory that results is a robust contender among current ethical theories. This illuminating book, relating Chinese and Western philosophical traditions, presents a unique account of the unity of the virtues in Mencius, breaks new ground in Hume studies through its discussion of the concept of sympathy in Hume's theory, and brings combined insights to bear on contemporary analytical theories of ethics.