
Great Books: The Foundation of a Liberal Education (1954)
The Meaning of Education and other Essays and Addresses https://books.google.com/books?id=H9cKAAAAIAAJ (1898) p. 45 as quoted by Robert Édouard Moritz, Memorabilia Mathematica; Or, The Philomath's Quotation-book https://books.google.com/books?id=G0wtAAAAYAAJ (1914)
Great Books: The Foundation of a Liberal Education (1954)
"Time in Transition" https://web.archive.org/web/20121113235339/http://www.thatsmags.com/shanghai/article/777/time-in-transition (2011) (original emphasis)
"Newton's Principia" in 300 Years of Gravitation. (1987) by S. W. Hawking and W. Israel, p. 4
The Notebooks of Leonardo da Vinci (1883), I Prolegomena and General Introduction to the Book on Painting
As quoted in Bigeometric Calculus: A System with a Scale-Free Derivative (1983) by Michael Grossman, and in Single Variable Calculus (1994) by James Stewart.
Report on the Theory of Numbers (1859) Part I, p. 59.
The Collected Mathematical Papers of Henry John Stephen Smith (1894) Vol. 1
Source: Mathematical Thought from Ancient to Modern Times (1972), p. 495