In Paradiso, Canto 4, Beatrice tells Dante,
You reason: ‘if my will to good persists,
why should the violence of others cause
the measure of my merit to be less?’
And you are also led to doubt because
the doctrine Plato taught would find support
by souls, appearing to return to the stars…
Timeus is a Platonic dialogue where each human soul has its own planet or star to which it repeatedly returns between different reincarnations until the perfect life is lived, and is able to dwell there in contentment forever, at least the part which is immortal (for Christians it’s the intellect). The quote from Timeus is as follows:
“The part of them worthy if the name immortal, which is called divine and is the guiding principal of those who are willing to follow just and you–of that part I will myself sow the seed, and having made a beginning, I will hand the work over to you. And do ye then interweave the mortal with the immortal and make and beget living creatures, and give them food and make them to grow, and receive them again in death.” Plato’s Timaeus, 41c-d
This is very close to Dante’s Christian belief that God creates some things directly and some things by an intermediary. Yet to yield to it one must deny that the body is good and holy and is to be resurrected and a human being is a union of body and soul. There’s often a belief that the body is something imperfect, and sinful, and that we must deny it, that it is carnal. However, that’s not how Dante sees it. So as Dante looks around the moon and sees shades to and fro, he senses dissonance in heaven’s kingdom. What I’m trying to convey is, the Timaeus refers to reincarnation, and the shedding of the body, and you receive a new body until a person lives the virtuous life. This fundamentally contradicts Christian belief, because we are connected to just one body, which the union between soul and body will be complete during resurrection. Beatrice says that the souls don’t dwell in the spheres but in the presence of God.
That which Timaeus said in reasoning
of souls does not describe what you have seen,
since it would seem that as he speaks he thinks.
He says the soul returns to that same star
from which–so he believes–it had been taken
when nature sent that soul as form to body;
but his opinion is, perhaps, to be
taken in other guise that his words speak,
intending something not to be derided.
Dante is trying to parse out the true from the untrue from the Timaeus again, and as he looks around he wonders if the stars do influence us after all, like Plato suggests. He still adamantly believes that the pagans went too far when they believed the planet and stars were actual gods.