Scheneewind, J.B. "Locke's Moral Philosophy," The Cambridge Companion to Locke. Ed. Vere Chappell, Cambridge, England: Cambridge University Press, 1994.

Excerpt:

“Friends as well as critics asked Locke several times to give a “plain explication” of his moral theory, but in his published writings he did not do so, and his rejections of his friends requests could be testy. Though one or two of Locke’s acquaintances knew that he had written extensive;y on natural law when he was a young Oxford don, suggestions that he revise or release the early work went unheeded. There is no doubt that Locke took compliance with the requirements of morality to be important for such happiness as we can attain in this life, and indispensable for reward in the next. Some of his remarks indicate, moreover, that he thought he had a comprehensive ethical theory explaining how reason could show what moral requirements we must satisfy; yet he left his readers to infer what this theory might be from a number of brief, scattered, and sometimes puzzling passages.”

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