"(The secret of unification, we will see, lies in expanding Riemann's metric to N-dimensional space and then chopping it up into rectangular pieces. Each rectangular piece corresponds to a different force. In this way, we can describe the various forces of nature by slotting them into the metric tensor like pieces of a puzzle. This is the mathematical expression of the principle that higher-dimensional space unifies the laws of nature, that there is "enough room" to unite them in N-dimensional space. More precisely, there is "enough room" in Riemann's metric to unite the forces of nature.)"