assumes the medieval view of the Universe, with the Earth surrounded by concentric spheres containing planets and stars.
The Paradiso begins at the top of
Mount Purgatory, called the
Earthly Paradise (i.e. the
Garden of Eden), at noon on Wednesday, March 30 (or April 13), 1300, following
Easter Sunday. Dante's journey through Paradise takes approximately twenty-four hours, which indicates that the entire journey of the Divine Comedy has taken one week, Thursday evening (Inferno I and II) to Thursday evening.
After ascending through the
sphere of fire believed to exist in the earth's upper atmosphere (Canto I),
Beatrice guides Dante through the nine
celestial spheres of
Heaven, to the
Empyrean, which is the abode of God. The nine spheres are concentric, as in the standard medieval
geocentric model of cosmology,
 which was derived from
Ptolemy. The Empyrean is non-material. As with his Purgatory, the structure of Dante's Heaven is therefore of the form 9+1=10, with one of the ten regions different in nature from the other nine.
During the course of his journey, Dante meets and converses with several blessed souls. He is careful to say that these all actually live in bliss with God in the Empyrean:
But all those souls grace the Empyrean;
and each of them has gentle life though some
sense the Eternal Spirit more, some less.
However, for Dante's benefit (and the benefit of his readers), he is "as a sign"
 shown various souls in planetary and stellar spheres that have some appropriate connotation.
While the structures of the
Purgatorio were based around different classifications of sin, the structure of the Paradiso is based on the four
cardinal virtues (
Fortitude) and the three
theological virtues (