- Pico della Mirandola, Conclusiones sive Theses DCCCC, 11th Mathematical Thesis: "By numbers, a way is had, to the searching out and understanding of everything able..."
- John Dee, Preface to Euclid, 39 (d.iij.) — On the Architect: "Architectura (sayth Vitruuius) est Scientia pluribus disciplinis & varijs eruditionibus ornata: cuius Iudicio probantur omnia, quæ ab cæteris..."
- Plato, Epinomis, 978.d: "Since Heaven never stops making these bodies ply their course night after night and day..."
- Marcus Aurelius, Meditations, Book 4:3.b: "Revisit the alternatives -- providence or atoms -- and the many indications that the universe..."
- Marcus Aurelius, Meditations, Book 4:40: "Think always of the universe as one living creature, comprising one substance and one soul:..."
- Marcus Aurelius, Meditations, Book 7:48: "When your talk is about mankind, view earthly things as if looking down on them..."
- Aristotle, Metaphysics, Book I, 987a13-19: "The Pythagoreans, while they likewise spoke of two principles, made this further addition, which is..."
- Aristotle, Metaphysics, Book XIV, 1090a20-5: "The Pythagoreans, on the other hand, observing that many attributes of numbers apply to sensible..."
- Vitruvius, De Architectura, Book I, Chapter I, Paragraphs 1-3: "The architect should be equipped with knowledge of many branches of study and varied kinds..."
- Vitruvius, De Architectura, Book II, Chapter II, Paragraph 1: "First of all Thales thought that water was the primordial substance of all things. Heraclitus..."
Natural philosophy was the philosophical study of nature and the physical universe that was dominant before the development of modern science. It can be considered the precursor of natural sciences such as physics.