The labor theory of value is fundamental to John Locke’s justification for property rights, but Edwin Hettinger argues in a famous article, “Justifying Intellectual Property,” that it fails to justify intellectual property rights. Hettinger believes that the labor theory of value cannot justify a right to the full economic value in an invention or book, because the creator’s physical labor contributes only proportionally to this socially-created market value. Robert Nozick, G. A. Cohen, and other philosophers similarly dismiss the labor theory of value as illogical or incoherent. But these philosophers redefine Locke’s concepts of labor and value into physical and economic terms, which is more akin to Karl Marx’s labor theory of economic value. The principle of interpretative charity demands reconsideration of Locke’s labor theory of value in its own terms and within the full context of his natural law ethical theory, especially in considering how Locke himself justifies intellectual property rights. This article thus analyzes oft-neglected portions of the text of the Second Treatise and integrates Locke’s property theory within the context of his natural law ethical theory, as presented in An Essay Concerning Human Understanding and in other works. In this context, Locke’s concept of labor means production, which has intellectual as well as physical characteristics, and his concept of value means that which is useful in the flourishing life of a rational being, which is a conception of the good that is more robust than merely physical status or economic wealth. This not only disabuses modern scholars of the absurdities they impose on Locke, it also explains why Locke says that inventions exemplify his labor-based property theory and why he argues for property rights in writings (copyrights), arguments that seem to have been lost on his critics in intellectual property theory and beyond.