In the second half of the 19th century, scientists and philosophers were involved in a heated discussion on the principles of geometry and on the validity of so-called non-Euclidean geometry.
Aasta teisel poolel, 19. sajandi teadlased ja filosoofid olid kaasatud soojendusega arutelu põhimõtteid geomeetria ja kehtivuse kohta nn mitte-eukleidiline geomeetria.