The 3-Sphere is a smoothed out surface of a hypercube: 3{\rm-sphere} = \partial(4{\rm-ball}) \approx \partial({\rm hypercube}) = \partial(\square\times\square) = (\box\times\square)\cup(\square\times\box) \approx (\circle\times\disc)\cup(\disc\times\circle) = Solid Torus + Solid Torus