Note 38 — LETTERS ON POLITICAL ECONOMY.
Reading edition
In the "Essays on Political Economy," since reprinted as "Munera Pulveris." See p. 10, § 12 of that book, where the passage is printed in italics: "The reader must, by anticipation, be warned against confusing value with cost, or with price. Value is the life-giving power of anything; cost, the quantity of labor required to produce it; price, the quantity of labor which its possessor will take in exchange for it."