A little bit of Literature

Dear friends and teachers...

I am struggling to figure out who wrote this book (centuries ago) in which we have this passage:

While I was returning to the
depths, one appeared, in front of my
eyes, who seemed hoarse from long
silence. When I saw him, in the
great emptiness, I cried out to him
?Have pity on me, whoever you are,
whether a man, in truth, or a
shadow!? He answered me: ?Not a
man: but a man I once was, and my
parents were Lombards, and both of
them, by their native place,
Mantuans.

Could you please help me out? Any comment will be very much appreciated!