Geometer's Sketchpad

"There is no royal road to geometry." "μή εἶναι βασιλικήν ἀτραπόν ἐπί γεωμετρίαν" "Non est regia [inquit Euclides] ad Geometriam via" – Reply given when the ruler Ptolemy I Soter asked Euclid if there was a shorter road to learning geometry than through Euclid's Elements.

"Geometry is almost the only subject as to which we find truths wherein all men agree; and one cause of this is, that geometers alone regard the true laws of demonstration." – Blaise Pascal, "Œuvres" (1845).

"A geometrician has learned to perform the most difficult demonstrations and calculations, as a monkey has learned to take his little hat off and on... All has been accomplished through signs, every species has learned…

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