Newton never called himself a scientist; the word did not exist yet
Isaac Newton's masterpiece of 1687 was titled Mathematical Principles of Natural Philosophy, because physics, chemistry and astronomy were all branches of philosophy then. The word scientist was only proposed in 1834. At Oxford and Aberdeen, natural philosophy still means physics on degree certificates.
From Aristotle until the 19th century, natural philosophy meant the reasoned study of the physical world, leaving aside supernatural causes. Philosophy was then the umbrella for every rational field. It differed from its sibling, natural history, which described and catalogued nature; natural philosophy tried to explain it, and after Galileo it increasingly did so with numbers. The Greeks confined it to the beings that make up the universe, excluding things people make, and Plato's dialogue Charmides already separated knowledge that produces physical results from knowledge that does not. Natural philosophy counted as theoretical, while crafts such as medicine and architecture applied it.
For centuries it was one strand of a general education rather than a specialism. Padua broke new ground in 1577 by naming Jacopo Zabarella its dedicated specialist in the subject, the first such appointment anywhere. In the 19th century, science acquired its modern sense of a rigorously experimental discipline with its own institutions, and William Whewell of Cambridge coined scientist to replace clumsy labels like cultivator of science. Still, Lord Kelvin and Peter Guthrie Tait titled their influential 1867 physics text Treatise on Natural Philosophy, and old chairs bearing the name are now mostly held by physicists.
German thinkers took a different path. Naturphilosophie, linked to Goethe, Schelling and Hegel and to Romanticism, sought a speculative unity of nature and spirit and pictured the world as a vast organism, in contrast to John Locke and others who saw it as a machine.
The subject raised deep puzzles. Parmenides and later Sextus Empiricus doubted that change is even real, and George Santayana argued it cannot be proved, implying a physicist must simply trust the senses. René Descartes split reality into deterministic matter, which belonged to natural philosophy, and free-willed mind, which lay outside it. The field's traditional branches ranged from cosmology and causation to chance, the infinite, motion, and the nature of space and time.
Source: Natural philosophy
