In this article by Rothbard, we find the following: "while liberals are in favor of any sexual activity engaged in by two consenting adults, when these consenting adults engage in trade or exchange, the liberals step in to harass, cripple, restrict, or prohibit that trade. And yet both the consenting sexual activity and the trade are similar expressions of liberty in action."
Nearly everyone in the philosophical profession thinks Nozick came up with the idea of "capitalist acts between consenting adults" in Anarchy, State, and Utopia. But here we find the same analogy used by Rothbard a year before (1973) Nozick's book came out (1974).
