“Time moves on but one axis,” advised Dr. Blope, “past to future—the only turnings possible being turns of a hundred and eighty degrees. In the Quaternions, a ninety-degree direction would correspond to an additional axis whose unit is √-1. A turn through any other angle would require for its unit a complex number.”
“Yet mappings in which a linear axis becomes curvilinear—functions of a complex variable such as w=ez, where a straight line in the z-plane maps to a circle in the w-plane,” said Dr. Rao, “do suggest the possibility of linear time becoming circular, and so achieving eternal return as simply, or should I say complexly, as that.”