I say, moreover, that Geometry,— speculative Geometry,—was extracted from practical Land Measuring. History informs us that this was so ;_that the Geometry of the Greeks arose out of the Land-Measuring of the Egyptians. And this is of itself most likely; for in every subject, Practice comes historically before Theory; Art before Science. Man acts first by the guidance of his practical Reason, and afterwards unfolds his convictions before the eye of his speculative Reason; thus striving to discern the Truths on which his action depends, and the Ideas which it involves. He constructs Squares and Pyramids and Ellipses, directed by his practical Geometrical Faculty; and then, by the aid of the same Faculty in a speculative form, he discovers the properties of Squares and Pyramids and Ellipses, and finds out demonstrations of these properties, and resolves these demonstrations into their simplest shapes, till he makes them depend upon Axioms, which all are ready to acknowledge after a little reflection, but which no one saw the true place of before. These Axioms are assented to by all thoughtful persons; and to say that they are assented to by all who have steadily considered them, is one of the simplest ways of saying that they are self-evident.
William Whewell, Lectures on Systematic Morality, Lesson V
