  In Dantean cosmography the Universe is described as a series of concentric
spheres with all the known planets embedded in their rotation motion, the Earth
located at the centre and Lucifer at the centre of the Earth. Beyond these
"celestial spheres", Dante represents the "angelic choirs" as other nine
spheres surrounding God. The rotation velocity increases with decreasing
distance from God, that is with increasing Power (Virtu'). We show that, adding
Power as an additional fourth dimension to space, the modern equations
governing the expansion of a closed Universe (i. e. with the density parameter
\Omega_0>1) in the space-time, can be applied to the medieval Universe as
imaged by Dante in his Divine Comedy. In this representation the Cosmos
acquires a unique description and Lucifer is not located at the centre of the
hyperspheres.
