The geometry of Tlön has two somewhat distinct systems, a visual one and a tactile one. The latter system corresponds to our geometry; they consider it inferior to the former. The foundation of visual geometry is the surface, not the point. This system rejects the principle of parallelism, and states that, as man moves about, he alters the forms which surround him. The arithmetical system is based on the idea of indefinite numbers. […] We already know that in Tlön the source of all-knowing is single and eternal.