Answer:
Dante included these lines to inform readers about what place does Brunetto holds in his life.
By this, readers will be able to know how Brunetto has been a guide for him in his political and literary career as well.
Step-by-step explanation:
'Inferno' is an epic poem written by Dante Alighieri in 14th century. The poem describes Dante's journey in Hell guided by Virgil.
In Canto XV, Dante included lines 55-61–
'And he to me: “If you pursue your star,
you cannot fail to reach a splendid harbor,
if in fair life, I judged you properly;
and if I had not died too soon for this,
on seeing Heaven was so kind to you,
I should have helped sustain you in your work.
But that malicious, that ungrateful people'–
to inform readers that what place does Brunetto holds in his life. Brunetto has guided Dante in his political and literary career while he was alive. Brunetto regrets to leave the earth so soon and unable to guide Dante. Brunetto, still, guides Dante to keep pursuing his 'star' and in doing so he will, one day, reach the harbor.
Through these lines, readers are able to know that Brunetto has been not a teacher to Dante in his literary career but his political career as well.