columnist Robert Samuelson argues "It’s time we tear up our economics textbooks and start over." He uses my book as a prime example. Perhaps not surprisingly, I disagree. My summary of Samuelson's article:Mr. Samuelson fails to fully appreciate the difference between journalism and textbook writing. Journalists are always looking for things that are new, for how the world has changed. That's why we call it the news. The editor of the science section of a newspaper would not be interested in a article explaining that Isaac Newton figured out the workings of gravity. Not newsworthy, the editor would say.Textbook writers, on the other hand, emphasize those things that are true, important, and unknown to the typical reader (an 18 year old college freshman). Newness has little relevance. The lessons of Adam Smith do not apply only to the 18th century, the lessons of David Ricardo do not apply only to the 19th century, and the lessons of John Maynard Keynes do not apply only to the 20th century. They are timeless ideas that may not make good news stories but should be central to introductory economics. Just as Newtonian mechanics should remain central to introductory physics.Yes, textbooks need to evolve as we learn more and as the world changes. New examples also show students how to apply the classic ideas to the issue of today. (The 9th edition of my principles text, available in about six months, includes a feature discussing social media like Facebook as a common resource.) But it would be a mistake for teachers of introductory economics to focus excessively on today's hot topics at the exclusion of timeless truths.I had a 6th grade teacher who used to refer to newspapers as a "perishable commodity." That seems right, given their relentless focus on newness. Good textbooks, however, are more like durable goods. They do not go out of date nearly as quickly.