How we cite our quotes:
[Virgil to Dante]: “Foolish is he who hopes our intellect
can reach the end of that unending road
only one Substance in three Persons follows.
Confine yourselves, o humans, to the quia;
had you been able to see all, there would
have been no need for Mary to give birth.
You saw the fruitless longing of those men
who would – if reason could – have been content,
those whose desire eternally laments:
I speak of Aristotle and of Plato –
and many others.” (Purg. III, 34-44)
Virgil reiterates that man cannot hope to fully understand God’s universe. His admonition for man to “confine [himself]…to the quia” (which is Latin for “what”) should remind us of Ulysses in Inferno, Canto XXVI, who sets sail as an old man, trying to “gain experience of the world / and of the vices and worth of men.” Because Ulysses tried to reach beyond the scope of men, God punishes him by condemning him to eternal damnation. Here, Virgil warns Dante of doing the same, but instead of comparing him to Ulysses, he compares Dante to “Aristotle and [...] Plato,” both confined to Limbo for trying to reach beyond the bounds of human reason.
Even as sheep that move, first one, then two,
then three, out of the fold – the others also
stand, eyes and muzzles lowered, timidly;
and what the first sheep does, the others do,
and if it halts, they huddle close behind,
simple and quiet and not knowing why…(Purg. III, 79-84)
It makes sense that the Excommunicates should be described as sheep in Purgatory. Because they were too rebellious in life – to the point of getting exiled by the Pope – here they pay for their crimes by taking the opposite role: being exceedingly meek. Here, it seems they do not think for themselves; instead of questioning things (as they did in life), they obediently follow the example of their leader.
[Virgil]: “Come, follow me, and let these people talk:
stand like a sturdy tower that does not shake
its summit though the winds may blast; always
the man in whom thought thrusts ahead of thought
allows the goal he’s set to move far off –
the force of one thought saps the other’s force.” (Purg. V, 13-18)
Virgil imparts a very relevant lesson to Dante. He urges his pupil to be firm in his resolution and to focus so that he does not become distracted from his ultimate goal. In his case, that means Dante should stop his ears to the gossip of others.