Irradiation Illusion
The Helmholtz 
in the 19th century. Despite the fact that the twoabove figures are identical in size, the white hole looks bigger than the black one in this Illusion.
References
Pappas, T. ``Irradiation Optical Illusion.'' The Joy of Mathematics. San Carlos, CA: Wide World Publ./Tetra, p. 199, 1989.
- Small Ditrigonal Dodecicosidodecahedron
- Small Ditrigonal Icosidodecahedron
- Small Dodecacronic Hexecontahedron
- Small Dodecahemicosacron
- Small Dodecahemicosahedron
- Small Dodecahemidodecacron
- Small Dodecahemidodecahedron
- Small Dodecicosacron
- Small Dodecicosahedron
- Small Dodecicosidodecahedron
- Small Hexacronic Icositetrahedron
- Small Hexagonal Hexecontahedron
- Small Hexagrammic Hexecontahedron
- Small Icosacronic Hexecontahedron
- Small Icosicosidodecahedron
- Small Icosihemidodecacron
- Small Icosihemidodecahedron
- Small Inverted Retrosnub Icosicosidodecahedron
- Axial Vector
- Axiom
- Axiom A Diffeomorphism
- Axiom A Flow
- Axiomatic Set Theory
- Axiomatic System
- Axiom of Choice