Historians, as a profession, are understandably fascinated by change. Civilizations, as a phenomenon, are properly concerned with conservation. Tension is inevitable when the former apply criteria of success and failure ill-suited to the goals of the latter. The best recent evidence: C-Span has just released its Presidential Historian’s Survey for 2017. It is proof that historians celebrate Presidents the more change they achieve while consigning them to obscurity for governing prudently according to circumstance.