In his book, Living Originalism, Jack Balkin proposes what he calls the “interaction theory” of the original semantic meaning of the word “commerce” in the Commerce Clause. He claims that “commerce” meant “social interaction.” In this article I show why this theory is wrong due to errors of commission and omission. Balkin is wrong to reduce “commerce” to “intercourse,” “intercourse” to “interaction,” and “interaction” to “affecting.” This triple reduction distorts rather than illuminates the original meaning of “commerce.” And Balkin omits from his discussion the massive amounts of evidence of contemporary usage—along with dictionary definitions of “intercourse”—establishing that “commerce” referred to the trade or transportation of things or persons, and did not include such productive economic activity as manufacturing or agriculture, much less all social interaction. In this article, I also reply to Balkin’s criticisms of my book, Restoring the Lost Constitution. I show how his heavy reliance on Gunning Bedford’s resolution in the secret Philadelphia convention is misplaced in a discussion of the original meaning of the Commerce Clause