Every science begins as philosophy and ends as art.

Durant is describing a recurring pattern in the history of knowledge. New fields begin as “philosophy” in the older sense: broad, speculative inquiry that asks foundational questions and lacks settled methods. As evidence accumulates, concepts sharpen and techniques become standardized; the field becomes a “science” with agreed procedures and testable claims. In maturity, its practice can resemble an “art”: not mere rule-following, but skilled judgment, intuition, and craft applied to complex realities (as in medicine, engineering, or statesmanship). The line also hints that the most advanced expertise often looks effortless and creative, even though it rests on rigorous, earlier theorizing.