Warren Buffett is American capitalism’s answer to Marcus Welby, the 1970s TV doctor who put a warm, matter-of-fact face on things that must be endured.

Mr. Buffett’s latest patient is Kraft Foods, agreeing last month to be purchased by Heinz, of which Mr. Buffett is a major shareholder. On TV, Mr. Buffett sang the praises of the incoming management. He explained the deal’s financing. He cheerfully signed off his CNBC interview by saying, “Keep putting plenty of ketchup on everything!”

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